fix(test): 修复CI测试失败

- 修复gofmt格式问题
- 为stubUsageLogRepo添加缺失的GetApiKeyStatsAggregated方法

backend/internal/repository/usage_log_repo.go

@@ -133,9 +133,9 @@ func (r *usageLogRepository) GetDashboardStats(ctx context.Context) (*DashboardS
 
 	// 合并用户统计查询
 	var userStats struct {
-		TotalUsers     int64 `gorm:"column:total_users"`
-		TodayNewUsers  int64 `gorm:"column:today_new_users"`
-		ActiveUsers    int64 `gorm:"column:active_users"`
+		TotalUsers    int64 `gorm:"column:total_users"`
+		TodayNewUsers int64 `gorm:"column:today_new_users"`
+		ActiveUsers   int64 `gorm:"column:active_users"`
 	}
 	if err := r.db.WithContext(ctx).Raw(`
 		SELECT
@@ -168,11 +168,11 @@ func (r *usageLogRepository) GetDashboardStats(ctx context.Context) (*DashboardS
 
 	// 合并账户统计查询
 	var accountStats struct {
-		TotalAccounts      int64 `gorm:"column:total_accounts"`
-		NormalAccounts     int64 `gorm:"column:normal_accounts"`
-		ErrorAccounts      int64 `gorm:"column:error_accounts"`
-		RateLimitAccounts  int64 `gorm:"column:ratelimit_accounts"`
-		OverloadAccounts   int64 `gorm:"column:overload_accounts"`
+		TotalAccounts     int64 `gorm:"column:total_accounts"`
+		NormalAccounts    int64 `gorm:"column:normal_accounts"`
+		ErrorAccounts     int64 `gorm:"column:error_accounts"`
+		RateLimitAccounts int64 `gorm:"column:ratelimit_accounts"`
+		OverloadAccounts  int64 `gorm:"column:overload_accounts"`
 	}
 	if err := r.db.WithContext(ctx).Raw(`
 		SELECT

backend/internal/server/api_contract_test.go

@@ -922,6 +922,10 @@ func (r *stubUsageLogRepo) GetUserUsageTrend(ctx context.Context, startTime, end
 	return nil, errors.New("not implemented")
 }
 
+func (r *stubUsageLogRepo) GetApiKeyStatsAggregated(ctx context.Context, apiKeyID int64, startTime, endTime time.Time) (*usagestats.UsageStats, error) {
+	return nil, errors.New("not implemented")
+}
+
 func (r *stubUsageLogRepo) GetBatchUserUsageStats(ctx context.Context, userIDs []int64) (map[int64]*usagestats.BatchUserUsageStats, error) {
 	return nil, errors.New("not implemented")
 }