feat: add affiliate invite rebate flow and admin rebate-rate setting

backend/internal/service/setting_service.go

@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"math"
 	"net/url"
 	"sort"
 	"strconv"
@@ -1167,6 +1168,8 @@ func (s *SettingService) buildSystemSettingsUpdates(ctx context.Context, setting
 	// 默认配置
 	updates[SettingKeyDefaultConcurrency] = strconv.Itoa(settings.DefaultConcurrency)
 	updates[SettingKeyDefaultBalance] = strconv.FormatFloat(settings.DefaultBalance, 'f', 8, 64)
+	settings.AffiliateRebateRate = clampAffiliateRebateRate(settings.AffiliateRebateRate)
+	updates[SettingKeyAffiliateRebateRate] = strconv.FormatFloat(settings.AffiliateRebateRate, 'f', 8, 64)
 	updates[SettingKeyDefaultUserRPMLimit] = strconv.Itoa(settings.DefaultUserRPMLimit)
 	defaultSubsJSON, err := json.Marshal(settings.DefaultSubscriptions)
 	if err != nil {
@@ -1719,6 +1722,7 @@ func (s *SettingService) InitializeDefaultSettings(ctx context.Context) error {
 		SettingKeyOIDCConnectUserInfoUsernamePath:          "",
 		SettingKeyDefaultConcurrency:                       strconv.Itoa(s.cfg.Default.UserConcurrency),
 		SettingKeyDefaultBalance:                           strconv.FormatFloat(s.cfg.Default.UserBalance, 'f', 8, 64),
+		SettingKeyAffiliateRebateRate:                      strconv.FormatFloat(AffiliateRebateRateDefault, 'f', 8, 64),
 		SettingKeyDefaultUserRPMLimit:                      "0",
 		SettingKeyDefaultSubscriptions:                     "[]",
 		SettingKeyAuthSourceDefaultEmailBalance:            "0",
@@ -1846,6 +1850,11 @@ func (s *SettingService) parseSettings(settings map[string]string) *SystemSettin
 	} else {
 		result.DefaultBalance = s.cfg.Default.UserBalance
 	}
+	if rebateRate, err := strconv.ParseFloat(settings[SettingKeyAffiliateRebateRate], 64); err == nil {
+		result.AffiliateRebateRate = clampAffiliateRebateRate(rebateRate)
+	} else {
+		result.AffiliateRebateRate = AffiliateRebateRateDefault
+	}
 	result.DefaultSubscriptions = parseDefaultSubscriptions(settings[SettingKeyDefaultSubscriptions])
 
 	// 敏感信息直接返回，方便测试连接时使用
@@ -2130,6 +2139,19 @@ func (s *SettingService) parseSettings(settings map[string]string) *SystemSettin
 	return result
 }
 
+func clampAffiliateRebateRate(value float64) float64 {
+	if math.IsNaN(value) || math.IsInf(value, 0) {
+		return AffiliateRebateRateDefault
+	}
+	if value < AffiliateRebateRateMin {
+		return AffiliateRebateRateMin
+	}
+	if value > AffiliateRebateRateMax {
+		return AffiliateRebateRateMax
+	}
+	return value
+}
+
 func isFalseSettingValue(value string) bool {
 	switch strings.ToLower(strings.TrimSpace(value)) {
 	case "false", "0", "off", "disabled":