refactor(database): 仓储边界 - 标注通用写入口与计费状态约束

backend/internal/repository/finance.go

@@ -438,6 +438,7 @@ func (r *Repository) MarkBillingRunning(id string) error {
 }
 
 func (r *Repository) MarkBillingUncertain(id string, errorText string) error {
+	// uncertain 保留冻结积分，直到人工核对；这里故意不自动结算或退款。
 	return r.db.Model(&model.BillingOrder{}).
 		Where("id = ? AND status IN ?", id, []model.BillingStatus{model.BillingStatusReserved, model.BillingStatusRunning}).
 		Updates(map[string]any{"status": model.BillingStatusUncertain, "error": errorText, "updated_at": time.Now()}).Error