支付确认强一致化: 订单推进与标 paid 合并为单事务

confirmPaid 原为「先 ConfirmPaidFromChannel 独立事务推进订单, 再 Updates 标 paid」两步非原子, 崩溃在中间会出现订单已 pending_handoff 但 payment 仍 paying 的不一致窗口, 恢复依赖渠道回调重发而非事务闭环。

改造:
- 新增 ConfirmPaidFromChannelTx(tx, orderID) 让 order 模块共享 payment 模块的外部事务, 订单推进与 payment 标 paid 落进同一事务, 崩溃一致性窗口消除
- NotifyNewConversation 提到事务提交后触发, 避免事务回滚后误发会话通知
- payment_orders 加行锁后 Updates, 防并发回调覆盖写
- 删除未使用的 providerBizNo 死参数

锁顺序全局一致 (order→listing→account→payment), 与 payment_start/refund/Cancel 路径无反向加锁, 无死锁风险。

新增集成测试:
- 正向: 验证 confirmPaid 后 order/listing/account/payment 全部正确推进
- 回滚: payment 更新失败时 order 不残留 pending_handoff, 验证事务原子性

go build/vet/test 通过。

backend/internal/modules/order/lifecycle.go

@@ -136,61 +136,12 @@ func (r *Repository) Pay(ctx context.Context, userID uint64, orderID uint64) err
 func (r *Repository) ConfirmPaidFromChannel(ctx context.Context, orderID uint64, providerBizNo string) error {
 	var newConvID uint64
 	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
-		assets, err := r.lockOrderAssets(tx, orderID)
+		convID, err := r.ConfirmPaidFromChannelTx(tx, orderID)
 		if err != nil {
 			return err
 		}
-		order := assets.Order
-		listing := assets.Listing
-		account := assets.Account
-		if order.Status == orderStatusPendingHandoff || order.Status == orderStatusRenting {
-			return nil
-		}
-		if order.Status != orderStatusPendingPayment {
-			return ErrOrderCannotPay
-		}
-
-		if listing.Status != listingStatusPublished || listing.ReviewStatus != listingReviewStatusApproved || !listing.InTransaction {
-			return ErrListingUnavailable
-		}
-
-		// 租客已通过外部渠道付款，这里不写租客钱包流水。
-		orderID := order.ID
-		order.Status = orderStatusPendingHandoff
-		order.HandoffStatus = handoffStatusPendingOwner
-		markAssetsRented(listing, account)
-		conv, err := chat.EnsureOrderConversation(tx, *order)
-		if err != nil {
-			return err
-		}
-		newConvID = conv.ID
-		if err := notification.Append(tx,
-			notification.Entry{
-				UserID:  order.OwnerID,
-				Type:    "order",
-				Title:   "收到新的租号订单",
-				Content: "租客已完成支付，请尽快提交交接说明。",
-				BizType: "order",
-				BizID:   &orderID,
-			},
-			notification.Entry{
-				UserID:  order.RenterID,
-				Type:    "order",
-				Title:   "订单支付成功",
-				Content: "支付已完成，等待号主提交交接说明。",
-				BizType: "order",
-				BizID:   &orderID,
-			},
-		); err != nil {
-			return err
-		}
-		if err := tx.Save(order).Error; err != nil {
-			return err
-		}
-		if err := tx.Save(listing).Error; err != nil {
-			return err
-		}
-		return tx.Save(account).Error
+		newConvID = convID
+		return nil
 	})
 	if err != nil {
 		return err
@@ -201,6 +152,68 @@ func (r *Repository) ConfirmPaidFromChannel(ctx context.Context, orderID uint64,
 	return nil
 }
 
+// ConfirmPaidFromChannelTx 在外部事务内推进支付成功后的订单状态。
+// 调用方负责提交事务，并在提交成功后按返回的会话 ID 触发异步通知。
+func (r *Repository) ConfirmPaidFromChannelTx(tx *gorm.DB, orderID uint64) (uint64, error) {
+	assets, err := r.lockOrderAssets(tx, orderID)
+	if err != nil {
+		return 0, err
+	}
+	order := assets.Order
+	listing := assets.Listing
+	account := assets.Account
+	if order.Status == orderStatusPendingHandoff || order.Status == orderStatusRenting {
+		return 0, nil
+	}
+	if order.Status != orderStatusPendingPayment {
+		return 0, ErrOrderCannotPay
+	}
+
+	if listing.Status != listingStatusPublished || listing.ReviewStatus != listingReviewStatusApproved || !listing.InTransaction {
+		return 0, ErrListingUnavailable
+	}
+
+	// 租客已通过外部渠道付款，这里不写租客钱包流水。
+	orderID = order.ID
+	order.Status = orderStatusPendingHandoff
+	order.HandoffStatus = handoffStatusPendingOwner
+	markAssetsRented(listing, account)
+	conv, err := chat.EnsureOrderConversation(tx, *order)
+	if err != nil {
+		return 0, err
+	}
+	if err := notification.Append(tx,
+		notification.Entry{
+			UserID:  order.OwnerID,
+			Type:    "order",
+			Title:   "收到新的租号订单",
+			Content: "租客已完成支付，请尽快提交交接说明。",
+			BizType: "order",
+			BizID:   &orderID,
+		},
+		notification.Entry{
+			UserID:  order.RenterID,
+			Type:    "order",
+			Title:   "订单支付成功",
+			Content: "支付已完成，等待号主提交交接说明。",
+			BizType: "order",
+			BizID:   &orderID,
+		},
+	); err != nil {
+		return 0, err
+	}
+	if err := tx.Save(order).Error; err != nil {
+		return 0, err
+	}
+	if err := tx.Save(listing).Error; err != nil {
+		return 0, err
+	}
+	if err := tx.Save(account).Error; err != nil {
+		return 0, err
+	}
+	return conv.ID, nil
+}
+
 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 {