优化退款审核逻辑：驳回分恢复订单/关闭订单两种，优化状态标签，清理无用脚本

- AdminRejectRefund 新增 action 参数：restore 恢复订单至待交接，close 关闭订单并下架
- 前端驳回改为弹窗双选项：仅驳回恢复订单 / 驳回并关闭
- 清空 frontend placeholder 文件
- handleFileUpload 并发控制优化：清空上传列表时重置计数和 OCR 槽位
- v-for key 改为 _id 避免预览串图
- preview-src-list 改为单图预览
- deploy-prod.sh 新增 docker image/builder prune 自动清理垃圾
- scripts/ 删除无用的压测文件（load_stress.go 等 4 个）

backend/internal/modules/order/service.go

@@ -236,14 +236,14 @@ func (s *Service) AdminApproveRefund(ctx context.Context, orderID uint64) error
 	return s.repo.AdminApproveRefund(ctx, orderID)
 }
 
-func (s *Service) AdminRejectRefund(ctx context.Context, orderID uint64) error {
+func (s *Service) AdminRejectRefund(ctx context.Context, orderID uint64, action string) error {
 	if s.repo == nil {
 		return ErrDependencyUnavailable
 	}
 	if orderID == 0 {
 		return ErrOrderCannotComplete
 	}
-	return s.repo.AdminRejectRefund(ctx, orderID)
+	return s.repo.AdminRejectRefund(ctx, orderID, action)
 }
 
 func (s *Service) ListPendingRefund(ctx context.Context) ([]OrderDTO, error) {