Merge pull request #5243 from wucm667/feat/issue-5240-dashboard-username

fix(dashboard): show usernames in spending ranking

backend/internal/pkg/usagestats/usage_log_types.go

@@ -149,6 +149,7 @@ type UserUsageTrendPoint struct {
 type UserSpendingRankingItem struct {
 	UserID     int64   `json:"user_id"`
 	Email      string  `json:"email"`
+	Username   string  `json:"username"`
 	ActualCost float64 `json:"actual_cost"` // 实际扣除
 	Requests   int64   `json:"requests"`
 	Tokens     int64   `json:"tokens"`