退款审核功能：待交接取消不再自动退款，改为客服审核后原路退回

- 租客在待交接状态取消订单不再自动退款，改为 refund_status=pending_review
- 新增退款审核页面 /admin/orders/refund-review，客服可逐个审核
- 新增 POST /refund/approve 通过退款、POST /refund/reject 驳回退款
- 新增 GET /orders/refund-pending 查询待审核退款订单列表
- 优化状态标签表述：已取消→租客已取消、已关闭→客服已关闭、异常→客服介入
- 新增 refund_status: pending_review 及其前端标签「待客服审核退款」
- AdminOrderDetailView 退款状态改用统一 refundStatusLabel

backend/internal/modules/order/lifecycle.go

@@ -227,7 +227,6 @@ func (r *Repository) ConfirmPaidFromChannelTx(tx *gorm.DB, orderID uint64) (uint
 }
 
 func (r *Repository) Cancel(ctx context.Context, userID uint64, orderID uint64) error {
-	var refund *refundAction
 	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
 		var order model.RentalOrder
 		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).
@@ -251,18 +250,16 @@ func (r *Repository) Cancel(ctx context.Context, userID uint64, orderID uint64)
 		orderID := order.ID
 		if beforeStatus == orderStatusPendingHandoff {
 			totalCent := order.RentAmountCent + order.DepositAmountCent
-			action, err := r.prepareRefund(&order, totalCent, refundBizCancel, "取消订单原路退款")
-			if err != nil {
-				return err
-			}
-			refund = action
+			order.RefundStatus = refundStatusPendingReview
+			order.RefundAmountCent = totalCent
+			order.RefundedAt = nil
 		}
 		if err := notification.Append(tx,
 			notification.Entry{
 				UserID:  order.OwnerID,
 				Type:    "order",
 				Title:   "订单已取消",
-				Content: "租客已取消订单，账号已重新释放。",
+				Content: "租客已取消订单，退款待客服审核。",
 				BizType: "order",
 				BizID:   &orderID,
 			},
@@ -270,7 +267,7 @@ func (r *Repository) Cancel(ctx context.Context, userID uint64, orderID uint64)
 				UserID:  order.RenterID,
 				Type:    "order",
 				Title:   "订单取消成功",
-				Content: "订单已取消，退款将原路退回您的支付账户。",
+				Content: "订单已取消，退款将由客服审核后原路退回。",
 				BizType: "order",
 				BizID:   &orderID,
 			},
@@ -293,7 +290,6 @@ func (r *Repository) Cancel(ctx context.Context, userID uint64, orderID uint64)
 	if err != nil {
 		return err
 	}
-	r.startRefundBestEffort(ctx, refund)
 	return nil
 }