feat(payment): add recharge fee rate setting and fix provider card UI

- Add recharge_fee_rate system setting (percentage fee on top of recharge amount)
- Full backend chain: config constant, PaymentConfig struct, update validation,
  read/write persistence, DTO, handler GET/PUT responses
- Frontend: settings input with preview, i18n (zh/en), API types
- Fix provider card toggle layout: labels above switches to save width
- Fix Chinese translation: "EasyPay" → "易支付" in provider description

backend/internal/handler/admin/setting_handler.go

@@ -189,6 +189,7 @@ func (h *SettingHandler) GetSettings(c *gin.Context) {
 		PaymentEnabledTypes:                  paymentCfg.EnabledTypes,
 		PaymentBalanceDisabled:               paymentCfg.BalanceDisabled,
 		PaymentBalanceRechargeMultiplier:     paymentCfg.BalanceRechargeMultiplier,
+		PaymentRechargeFeeRate:              paymentCfg.RechargeFeeRate,
 		PaymentLoadBalanceStrat:              paymentCfg.LoadBalanceStrategy,
 		PaymentProductNamePrefix:             paymentCfg.ProductNamePrefix,
 		PaymentProductNameSuffix:             paymentCfg.ProductNameSuffix,
@@ -327,6 +328,7 @@ type UpdateSettingsRequest struct {
 	PaymentEnabledTypes              []string `json:"payment_enabled_types"`
 	PaymentBalanceDisabled           *bool    `json:"payment_balance_disabled"`
 	PaymentBalanceRechargeMultiplier *float64 `json:"payment_balance_recharge_multiplier"`
+	PaymentRechargeFeeRate              *float64 `json:"payment_recharge_fee_rate"`
 	PaymentLoadBalanceStrat          *string  `json:"payment_load_balance_strategy"`
 	PaymentProductNamePrefix *string  `json:"payment_product_name_prefix"`
 	PaymentProductNameSuffix *string  `json:"payment_product_name_suffix"`
@@ -945,6 +947,7 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 			EnabledTypes:              req.PaymentEnabledTypes,
 			BalanceDisabled:           req.PaymentBalanceDisabled,
 			BalanceRechargeMultiplier: req.PaymentBalanceRechargeMultiplier,
+			RechargeFeeRate:          req.PaymentRechargeFeeRate,
 			LoadBalanceStrategy:       req.PaymentLoadBalanceStrat,
 			ProductNamePrefix:         req.PaymentProductNamePrefix,
 			ProductNameSuffix:         req.PaymentProductNameSuffix,
@@ -1086,6 +1089,7 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 		PaymentEnabledTypes:                  updatedPaymentCfg.EnabledTypes,
 		PaymentBalanceDisabled:               updatedPaymentCfg.BalanceDisabled,
 		PaymentBalanceRechargeMultiplier:     updatedPaymentCfg.BalanceRechargeMultiplier,
+		PaymentRechargeFeeRate:              updatedPaymentCfg.RechargeFeeRate,
 		PaymentLoadBalanceStrat:              updatedPaymentCfg.LoadBalanceStrategy,
 		PaymentProductNamePrefix:             updatedPaymentCfg.ProductNamePrefix,
 		PaymentProductNameSuffix:             updatedPaymentCfg.ProductNameSuffix,
@@ -1105,7 +1109,7 @@ func hasPaymentFields(req UpdateSettingsRequest) bool {
 		req.PaymentMaxAmount != nil || req.PaymentDailyLimit != nil ||
 		req.PaymentOrderTimeoutMin != nil || req.PaymentMaxPendingOrders != nil ||
 		req.PaymentEnabledTypes != nil || req.PaymentBalanceDisabled != nil ||
-		req.PaymentBalanceRechargeMultiplier != nil ||
+		req.PaymentBalanceRechargeMultiplier != nil || req.PaymentRechargeFeeRate != nil ||
 		req.PaymentLoadBalanceStrat != nil || req.PaymentProductNamePrefix != nil ||
 		req.PaymentProductNameSuffix != nil || req.PaymentHelpImageURL != nil ||
 		req.PaymentHelpText != nil || req.PaymentCancelRateLimitEnabled != nil ||

backend/internal/handler/dto/settings.go

@@ -137,6 +137,7 @@ type SystemSettings struct {
 	PaymentEnabledTypes              []string `json:"payment_enabled_types"`
 	PaymentBalanceDisabled           bool     `json:"payment_balance_disabled"`
 	PaymentBalanceRechargeMultiplier float64  `json:"payment_balance_recharge_multiplier"`
+	PaymentRechargeFeeRate              float64  `json:"payment_recharge_fee_rate"`
 	PaymentLoadBalanceStrat          string   `json:"payment_load_balance_strategy"`
 	PaymentProductNamePrefix string   `json:"payment_product_name_prefix"`
 	PaymentProductNameSuffix string   `json:"payment_product_name_suffix"`

backend/internal/handler/payment_handler.go

@@ -132,6 +132,7 @@ func (h *PaymentHandler) GetCheckoutInfo(c *gin.Context) {
 		Plans:                     planList,
 		BalanceDisabled:           cfg.BalanceDisabled,
 		BalanceRechargeMultiplier: cfg.BalanceRechargeMultiplier,
+		RechargeFeeRate:           cfg.RechargeFeeRate,
 		HelpText:                  cfg.HelpText,
 		HelpImageURL:              cfg.HelpImageURL,
 		StripePublishableKey:      cfg.StripePublishableKey,
@@ -145,6 +146,7 @@ type checkoutInfoResponse struct {
 	Plans                     []checkoutPlan                  `json:"plans"`
 	BalanceDisabled           bool                            `json:"balance_disabled"`
 	BalanceRechargeMultiplier float64                         `json:"balance_recharge_multiplier"`
+	RechargeFeeRate           float64                         `json:"recharge_fee_rate"`
 	HelpText                  string                          `json:"help_text"`
 	HelpImageURL              string                          `json:"help_image_url"`
 	StripePublishableKey      string                          `json:"stripe_publishable_key"`

backend/internal/service/payment_config_service.go

@@ -24,6 +24,7 @@ const (
 	SettingLoadBalanceStrategy = "LOAD_BALANCE_STRATEGY"
 	SettingBalancePayDisabled  = "BALANCE_PAYMENT_DISABLED"
 	SettingBalanceRechargeMult = "BALANCE_RECHARGE_MULTIPLIER"
+	SettingRechargeFeeRate    = "RECHARGE_FEE_RATE"
 	SettingProductNamePrefix   = "PRODUCT_NAME_PREFIX"
 	SettingProductNameSuffix   = "PRODUCT_NAME_SUFFIX"
 	SettingHelpImageURL        = "PAYMENT_HELP_IMAGE_URL"
@@ -52,6 +53,7 @@ type PaymentConfig struct {
 	EnabledTypes              []string `json:"enabled_payment_types"`
 	BalanceDisabled           bool     `json:"balance_disabled"`
 	BalanceRechargeMultiplier float64  `json:"balance_recharge_multiplier"`
+	RechargeFeeRate          float64  `json:"recharge_fee_rate"`
 	LoadBalanceStrategy       string   `json:"load_balance_strategy"`
 	ProductNamePrefix    string   `json:"product_name_prefix"`
 	ProductNameSuffix    string   `json:"product_name_suffix"`
@@ -78,6 +80,7 @@ type UpdatePaymentConfigRequest struct {
 	EnabledTypes              []string `json:"enabled_payment_types"`
 	BalanceDisabled           *bool    `json:"balance_disabled"`
 	BalanceRechargeMultiplier *float64 `json:"balance_recharge_multiplier"`
+	RechargeFeeRate          *float64 `json:"recharge_fee_rate"`
 	LoadBalanceStrategy       *string  `json:"load_balance_strategy"`
 	ProductNamePrefix   *string  `json:"product_name_prefix"`
 	ProductNameSuffix   *string  `json:"product_name_suffix"`
@@ -188,7 +191,7 @@ func (s *PaymentConfigService) GetPaymentConfig(ctx context.Context) (*PaymentCo
 	keys := []string{
 		SettingPaymentEnabled, SettingMinRechargeAmount, SettingMaxRechargeAmount,
 		SettingDailyRechargeLimit, SettingOrderTimeoutMinutes, SettingMaxPendingOrders,
-		SettingEnabledPaymentTypes, SettingBalancePayDisabled, SettingBalanceRechargeMult, SettingLoadBalanceStrategy,
+		SettingEnabledPaymentTypes, SettingBalancePayDisabled, SettingBalanceRechargeMult, SettingRechargeFeeRate, SettingLoadBalanceStrategy,
 		SettingProductNamePrefix, SettingProductNameSuffix,
 		SettingHelpImageURL, SettingHelpText,
 		SettingCancelRateLimitOn, SettingCancelRateLimitMax,
@@ -214,6 +217,7 @@ func (s *PaymentConfigService) parsePaymentConfig(vals map[string]string) *Payme
 		MaxPendingOrders:    pcParseInt(vals[SettingMaxPendingOrders], defaultMaxPendingOrders),
 		BalanceDisabled:           vals[SettingBalancePayDisabled] == "true",
 		BalanceRechargeMultiplier: normalizeBalanceRechargeMultiplier(pcParseFloat(vals[SettingBalanceRechargeMult], defaultBalanceRechargeMultiplier)),
+		RechargeFeeRate:          pcParseFloat(vals[SettingRechargeFeeRate], 0),
 		LoadBalanceStrategy:       vals[SettingLoadBalanceStrategy],
 		ProductNamePrefix:   vals[SettingProductNamePrefix],
 		ProductNameSuffix:   vals[SettingProductNameSuffix],
@@ -267,6 +271,11 @@ func (s *PaymentConfigService) UpdatePaymentConfig(ctx context.Context, req Upda
 			return infraerrors.BadRequest("INVALID_BALANCE_RECHARGE_MULTIPLIER", "balance recharge multiplier must be greater than 0")
 		}
 	}
+	if req.RechargeFeeRate != nil {
+		if math.IsNaN(*req.RechargeFeeRate) || math.IsInf(*req.RechargeFeeRate, 0) || *req.RechargeFeeRate < 0 {
+			return infraerrors.BadRequest("INVALID_RECHARGE_FEE_RATE", "recharge fee rate must be >= 0")
+		}
+	}
 	m := map[string]string{
 		SettingPaymentEnabled:      formatBoolOrEmpty(req.Enabled),
 		SettingMinRechargeAmount:   formatPositiveFloat(req.MinAmount),
@@ -276,6 +285,7 @@ func (s *PaymentConfigService) UpdatePaymentConfig(ctx context.Context, req Upda
 		SettingMaxPendingOrders:    formatPositiveInt(req.MaxPendingOrders),
 		SettingBalancePayDisabled:  formatBoolOrEmpty(req.BalanceDisabled),
 		SettingBalanceRechargeMult: formatPositiveFloat(req.BalanceRechargeMultiplier),
+		SettingRechargeFeeRate:    formatNonNegativeFloat(req.RechargeFeeRate),
 		SettingLoadBalanceStrategy: derefStr(req.LoadBalanceStrategy),
 		SettingProductNamePrefix:   derefStr(req.ProductNamePrefix),
 		SettingProductNameSuffix:   derefStr(req.ProductNameSuffix),
@@ -309,6 +319,13 @@ func formatPositiveFloat(v *float64) string {
 	return strconv.FormatFloat(*v, 'f', 2, 64)
 }
 
+func formatNonNegativeFloat(v *float64) string {
+	if v == nil || *v < 0 {
+		return ""
+	}
+	return strconv.FormatFloat(*v, 'f', 2, 64)
+}
+
 func formatPositiveInt(v *int) string {
 	if v == nil || *v <= 0 {
 		return ""

frontend/src/api/admin/settings.ts

@@ -126,6 +126,7 @@ export interface SystemSettings {
   payment_enabled_types: string[]
   payment_balance_disabled: boolean
   payment_balance_recharge_multiplier: number
+  payment_recharge_fee_rate: number
   payment_load_balance_strategy: string
   payment_product_name_prefix: string
   payment_product_name_suffix: string
@@ -233,6 +234,7 @@ export interface UpdateSettingsRequest {
   payment_enabled_types?: string[]
   payment_balance_disabled?: boolean
   payment_balance_recharge_multiplier?: number
+  payment_recharge_fee_rate?: number
   payment_load_balance_strategy?: string
   payment_product_name_prefix?: string
   payment_product_name_suffix?: string

frontend/src/components/payment/ToggleSwitch.vue

@@ -1,6 +1,6 @@
 <template>
-  <label class="flex items-center gap-1.5 cursor-pointer">
+  <label class="flex flex-col items-center gap-0.5 cursor-pointer">
-    <span class="text-xs text-gray-500 dark:text-gray-400">{{ label }}</span>
+    <span class="text-xs text-gray-500 dark:text-gray-400 whitespace-nowrap">{{ label }}</span>
     <button
       type="button"
       role="switch"

frontend/src/i18n/locales/en.ts

@@ -4569,6 +4569,9 @@ export default {
         balanceRechargeMultiplier: 'Balance Recharge Multiplier',
         balanceRechargeMultiplierHint: 'How many USD balance the user receives for each 1 CNY paid',
         balanceRechargePreview: 'Preview: 1 CNY = {usd} USD',
+        rechargeFeeRate: 'Recharge Fee Rate',
+        rechargeFeeRateHint: 'Percentage of service fee charged on top of recharge amount, 0 means no fee',
+        rechargeFeePreview: 'Preview: Recharge 100, fee {fee}',
         orderTimeout: 'Order Timeout',
         orderTimeoutHint: 'In minutes, minimum 1',
         maxPendingOrders: 'Max Pending Orders',

frontend/src/i18n/locales/zh.ts

@@ -4726,13 +4726,16 @@ export default {
         enabledHint: '启用或禁用支付系统',
         enabledPaymentTypes: '启用的服务商',
         enabledPaymentTypesHint: '禁用服务商将同时禁用对应的实例。',
-        findProvider: '正在寻找合适的 EasyPay 服务商？',
+        findProvider: '正在寻找合适的易支付服务商？',
         minAmount: '最低金额',
         maxAmount: '最高金额',
         dailyLimit: '每日限额',
         balanceRechargeMultiplier: '余额充值倍率',
         balanceRechargeMultiplierHint: '用户每支付 1 CNY 可获得多少 USD 余额',
         balanceRechargePreview: '预览：1 CNY = {usd} USD',
+        rechargeFeeRate: '充值手续费率',
+        rechargeFeeRateHint: '用户充值时额外收取的手续费百分比，0 表示不收取手续费',
+        rechargeFeePreview: '预览：充值 100 元，手续费 {fee} 元',
         orderTimeout: '订单超时时间',
         orderTimeoutHint: '单位：分钟，至少 1 分钟',
         maxPendingOrders: '最大待支付订单数',

frontend/src/views/admin/SettingsView.vue

@@ -2381,6 +2381,12 @@
                   <p class="mt-0.5 text-xs text-gray-400">{{ t('admin.settings.payment.balanceRechargeMultiplierHint') }}</p>
                   <p class="mt-1 text-xs font-medium text-primary-600 dark:text-primary-400">{{ t('admin.settings.payment.balanceRechargePreview', { usd: (Number(form.payment_balance_recharge_multiplier) || 1).toFixed(2) }) }}</p>
                 </div>
+                <div>
+                  <label class="input-label">{{ t('admin.settings.payment.rechargeFeeRate') }}</label>
+                  <input :value="form.payment_recharge_fee_rate || ''" @input="form.payment_recharge_fee_rate = parseFloat(($event.target as HTMLInputElement).value) || 0" type="number" step="0.01" min="0" class="input" />
+                  <p class="mt-0.5 text-xs text-gray-400">{{ t('admin.settings.payment.rechargeFeeRateHint') }}</p>
+                  <p v-if="(Number(form.payment_recharge_fee_rate) || 0) > 0" class="mt-1 text-xs font-medium text-primary-600 dark:text-primary-400">{{ t('admin.settings.payment.rechargeFeePreview', { fee: (Number(form.payment_recharge_fee_rate) || 0).toFixed(2) }) }}</p>
+                </div>
                 <div><label class="input-label">{{ t('admin.settings.payment.orderTimeout') }} <span class="text-red-500">*</span></label><input v-model.number="form.payment_order_timeout_minutes" type="number" min="1" class="input" required /><p class="mt-0.5 text-xs text-gray-400">{{ t('admin.settings.payment.orderTimeoutHint') }}</p></div>
               </div>
               <!-- Row 3: Pending orders + load balance + cancel rate limit (all in one row) -->
@@ -2974,7 +2980,7 @@ const form = reactive<SettingsForm>({
   home_content: '',
   backend_mode_enabled: false,
   hide_ccs_import_button: false,
-  payment_enabled: false,  payment_min_amount: 1,  payment_max_amount: 10000,  payment_daily_limit: 50000,  payment_max_pending_orders: 3,  payment_order_timeout_minutes: 30,  payment_balance_disabled: false,  payment_balance_recharge_multiplier: 1,  payment_enabled_types: [],  payment_help_image_url: '',  payment_help_text: '',  payment_product_name_prefix: '',  payment_product_name_suffix: '',  payment_load_balance_strategy: 'round-robin',  payment_cancel_rate_limit_enabled: false,  payment_cancel_rate_limit_max: 10,  payment_cancel_rate_limit_window: 1,  payment_cancel_rate_limit_unit: 'day',  payment_cancel_rate_limit_window_mode: 'rolling',
+  payment_enabled: false,  payment_min_amount: 1,  payment_max_amount: 10000,  payment_daily_limit: 50000,  payment_max_pending_orders: 3,  payment_order_timeout_minutes: 30,  payment_balance_disabled: false,  payment_balance_recharge_multiplier: 1,  payment_recharge_fee_rate: 0,  payment_enabled_types: [],  payment_help_image_url: '',  payment_help_text: '',  payment_product_name_prefix: '',  payment_product_name_suffix: '',  payment_load_balance_strategy: 'round-robin',  payment_cancel_rate_limit_enabled: false,  payment_cancel_rate_limit_max: 10,  payment_cancel_rate_limit_window: 1,  payment_cancel_rate_limit_unit: 'day',  payment_cancel_rate_limit_window_mode: 'rolling',
   table_default_page_size: tablePageSizeDefault,
   table_page_size_options: [10, 20, 50, 100],
   custom_menu_items: [] as Array<{id: string; label: string; icon_svg: string; url: string; visibility: 'user' | 'admin'; sort_order: number}>,
@@ -3634,6 +3640,7 @@ async function saveSettings() {
       payment_order_timeout_minutes: Number(form.payment_order_timeout_minutes) || 0,
       payment_balance_disabled: form.payment_balance_disabled,
       payment_balance_recharge_multiplier: Number(form.payment_balance_recharge_multiplier) || 1,
+      payment_recharge_fee_rate: Number(form.payment_recharge_fee_rate) || 0,
       payment_enabled_types: form.payment_enabled_types,
       payment_load_balance_strategy: form.payment_load_balance_strategy,
       payment_product_name_prefix: form.payment_product_name_prefix,