feat(channel-monitor): add feature switch settings + fix extra_models save

Settings:
- New "功能开关" tab between 通用设置 and 安全与认证
- ChannelMonitorEnabled toggle: runner skips scheduling when false,
  user-facing list returns empty
- ChannelMonitorDefaultIntervalSeconds (15-3600): pre-fills interval
  when creating a new monitor; each monitor can still override

Bug fix:
- ModelTagInput now commits pending input on blur, not just Enter/Tab.
  Previously clicking "save" with an un-Enter'd extra model would drop
  the value (DB stored extra_models=[] even when user typed entries).

Backend:
- domain_constants: SettingKeyChannelMonitor{Enabled,DefaultIntervalSeconds}
- SettingService.GetChannelMonitorRuntime: lightweight getter used by
  runner tick + user handler per-request (fail-open on DB error)
- Runner tickDueChecks: bails early when feature disabled
- ChannelMonitorUserHandler: checks feature flag before serving
- Comment on runner doc: scheduler state is implicit (every tick re-reads
  ListEnabled from DB), so CRUD ops on monitors self-maintain the schedule

Bump VERSION to 0.1.114.25

backend/internal/handler/admin/setting_handler.go

@@ -235,6 +235,9 @@ func (h *SettingHandler) GetSettings(c *gin.Context) {
 		PaymentCancelRateLimitWindow:           paymentCfg.CancelRateLimitWindow,
 		PaymentCancelRateLimitUnit:             paymentCfg.CancelRateLimitUnit,
 		PaymentCancelRateLimitMode:             paymentCfg.CancelRateLimitMode,
+
+		ChannelMonitorEnabled:                settings.ChannelMonitorEnabled,
+		ChannelMonitorDefaultIntervalSeconds: settings.ChannelMonitorDefaultIntervalSeconds,
 	}
 	response.Success(c, systemSettingsResponseData(payload, authSourceDefaults))
 }
@@ -425,6 +428,10 @@ type UpdateSettingsRequest struct {
 	PaymentCancelRateLimitWindow  *int    `json:"payment_cancel_rate_limit_window"`
 	PaymentCancelRateLimitUnit    *string `json:"payment_cancel_rate_limit_unit"`
 	PaymentCancelRateLimitMode    *string `json:"payment_cancel_rate_limit_window_mode"`
+
+	// Channel Monitor feature switch
+	ChannelMonitorEnabled                *bool `json:"channel_monitor_enabled"`
+	ChannelMonitorDefaultIntervalSeconds *int  `json:"channel_monitor_default_interval_seconds"`
 }
 
 // UpdateSettings 更新系统设置
@@ -1219,6 +1226,18 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 			}
 			return previousSettings.AccountQuotaNotifyEmails
 		}(),
+		ChannelMonitorEnabled: func() bool {
+			if req.ChannelMonitorEnabled != nil {
+				return *req.ChannelMonitorEnabled
+			}
+			return previousSettings.ChannelMonitorEnabled
+		}(),
+		ChannelMonitorDefaultIntervalSeconds: func() int {
+			if req.ChannelMonitorDefaultIntervalSeconds != nil {
+				return *req.ChannelMonitorDefaultIntervalSeconds
+			}
+			return previousSettings.ChannelMonitorDefaultIntervalSeconds
+		}(),
 	}
 
 	authSourceDefaults := &service.AuthSourceDefaultSettings{
@@ -1449,6 +1468,9 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 		PaymentCancelRateLimitWindow:           updatedPaymentCfg.CancelRateLimitWindow,
 		PaymentCancelRateLimitUnit:             updatedPaymentCfg.CancelRateLimitUnit,
 		PaymentCancelRateLimitMode:             updatedPaymentCfg.CancelRateLimitMode,
+
+		ChannelMonitorEnabled:                updatedSettings.ChannelMonitorEnabled,
+		ChannelMonitorDefaultIntervalSeconds: updatedSettings.ChannelMonitorDefaultIntervalSeconds,
 	}
 	response.Success(c, systemSettingsResponseData(payload, updatedAuthSourceDefaults))
 }
@@ -1805,6 +1827,12 @@ func diffSettings(before *service.SystemSettings, after *service.SystemSettings,
 	if !equalNotifyEmailEntries(before.AccountQuotaNotifyEmails, after.AccountQuotaNotifyEmails) {
 		changed = append(changed, "account_quota_notify_emails")
 	}
+	if before.ChannelMonitorEnabled != after.ChannelMonitorEnabled {
+		changed = append(changed, "channel_monitor_enabled")
+	}
+	if before.ChannelMonitorDefaultIntervalSeconds != after.ChannelMonitorDefaultIntervalSeconds {
+		changed = append(changed, "channel_monitor_default_interval_seconds")
+	}
 	changed = appendAuthSourceDefaultChanges(changed, beforeAuthSourceDefaults, afterAuthSourceDefaults)
 	return changed
 }

backend/internal/handler/channel_monitor_user_handler.go

@@ -14,11 +14,28 @@ import (
 // ChannelMonitorUserHandler 渠道监控用户只读 handler。
 type ChannelMonitorUserHandler struct {
 	monitorService *service.ChannelMonitorService
+	settingService *service.SettingService
 }
 
 // NewChannelMonitorUserHandler 创建 handler。
-func NewChannelMonitorUserHandler(monitorService *service.ChannelMonitorService) *ChannelMonitorUserHandler {
-	return &ChannelMonitorUserHandler{monitorService: monitorService}
+// settingService 用于每次请求前读取功能开关；关闭时 List/GetStatus 直接返回空/404。
+func NewChannelMonitorUserHandler(
+	monitorService *service.ChannelMonitorService,
+	settingService *service.SettingService,
+) *ChannelMonitorUserHandler {
+	return &ChannelMonitorUserHandler{
+		monitorService: monitorService,
+		settingService: settingService,
+	}
+}
+
+// featureEnabled 返回当前渠道监控功能是否开启。
+// settingService 为 nil（测试场景）视为启用。
+func (h *ChannelMonitorUserHandler) featureEnabled(c *gin.Context) bool {
+	if h.settingService == nil {
+		return true
+	}
+	return h.settingService.GetChannelMonitorRuntime(c.Request.Context()).Enabled
 }
 
 // --- Response ---
@@ -123,6 +140,10 @@ func userMonitorDetailToResponse(d *service.UserMonitorDetail) *channelMonitorUs
 
 // List GET /api/v1/channel-monitors
 func (h *ChannelMonitorUserHandler) List(c *gin.Context) {
+	if !h.featureEnabled(c) {
+		response.Success(c, gin.H{"items": []channelMonitorUserListItem{}})
+		return
+	}
 	views, err := h.monitorService.ListUserView(c.Request.Context())
 	if err != nil {
 		response.ErrorFrom(c, err)
@@ -137,6 +158,10 @@ func (h *ChannelMonitorUserHandler) List(c *gin.Context) {
 
 // GetStatus GET /api/v1/channel-monitors/:id/status
 func (h *ChannelMonitorUserHandler) GetStatus(c *gin.Context) {
+	if !h.featureEnabled(c) {
+		response.ErrorFrom(c, service.ErrChannelMonitorNotFound)
+		return
+	}
 	// 复用 admin.ParseChannelMonitorID 保持错误码与日志一致。
 	id, ok := admin.ParseChannelMonitorID(c)
 	if !ok {

backend/internal/handler/dto/settings.go

@@ -183,6 +183,10 @@ type SystemSettings struct {
 	BalanceLowNotifyRechargeURL string             `json:"balance_low_notify_recharge_url"`
 	AccountQuotaNotifyEnabled   bool               `json:"account_quota_notify_enabled"`
 	AccountQuotaNotifyEmails    []NotifyEmailEntry `json:"account_quota_notify_emails"`
+
+	// Channel Monitor feature switch
+	ChannelMonitorEnabled                bool `json:"channel_monitor_enabled"`
+	ChannelMonitorDefaultIntervalSeconds int  `json:"channel_monitor_default_interval_seconds"`
 }
 
 type DefaultSubscriptionSetting struct {
@@ -230,6 +234,9 @@ type PublicSettings struct {
 	AccountQuotaNotifyEnabled        bool             `json:"account_quota_notify_enabled"`
 	BalanceLowNotifyThreshold        float64          `json:"balance_low_notify_threshold"`
 	BalanceLowNotifyRechargeURL      string           `json:"balance_low_notify_recharge_url"`
+
+	ChannelMonitorEnabled                bool `json:"channel_monitor_enabled"`
+	ChannelMonitorDefaultIntervalSeconds int  `json:"channel_monitor_default_interval_seconds"`
 }
 
 // OverloadCooldownSettings 529过载冷却配置 DTO

backend/internal/handler/setting_handler.go

@@ -70,5 +70,8 @@ func (h *SettingHandler) GetPublicSettings(c *gin.Context) {
 		AccountQuotaNotifyEnabled:        settings.AccountQuotaNotifyEnabled,
 		BalanceLowNotifyThreshold:        settings.BalanceLowNotifyThreshold,
 		BalanceLowNotifyRechargeURL:      settings.BalanceLowNotifyRechargeURL,
+
+		ChannelMonitorEnabled:                settings.ChannelMonitorEnabled,
+		ChannelMonitorDefaultIntervalSeconds: settings.ChannelMonitorDefaultIntervalSeconds,
 	})
 }