fix: stabilize backend tests

backend/app/services/wallet.go

@@ -3,6 +3,7 @@ package services
 import (
 	"context"
 	"errors"
+	"strconv"
 	"time"
 
 	"quyun/v2/app/errorx"
@@ -104,6 +105,6 @@ func (s *wallet) Recharge(
 	// Mock Pay Params
 	return &user_dto.RechargeResponse{
 		PayParams: "mock_paid_success",
-		OrderID:   order.ID,
+		OrderID:   strconv.FormatInt(order.ID, 10),
 	}, nil
 }