fix(chat): 分销付款改为进入账号群，不再另建订单群

主站、分站和分站之间都只用发布时的账号群，二维码仍跟这个群走。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/internal/modules/order/lifecycle.go

@@ -358,25 +358,17 @@ func (r *Repository) ConfirmPaidFromChannelTx(tx *gorm.DB, orderID uint64) (uint
 		return 0, err
 	}
 
-	// 分销订单创建独立分站群聊；主站订单拉租客进发布群
+	// 付款后只拉租客进账号群。主站和分销都不再另建订单群，二维码仍是发布时分到这个群的那一张。
 	conversationID := uint64(0)
-	if order.DistributionSiteID != nil && *order.DistributionSiteID > 0 {
-		orderConv, err := chat.EnsureOrderConversation(tx, *order)
-		if err != nil {
-			return 0, err
-		}
-		if orderConv != nil {
-			conversationID = orderConv.ID
-		}
-	} else {
-		if err := chat.AddRenterToListingConversation(tx, listing.ID, order.RenterID, order.OrderNo); err != nil {
-			return 0, err
-		}
-		// 查询发布群ID用于返回
-		var listingConv model.ChatConversation
-		if err := tx.Where("listing_id = ?", listing.ID).First(&listingConv).Error; err == nil {
-			conversationID = listingConv.ID
-		}
+	if err := chat.AddRenterToListingConversation(tx, listing.ID, order.RenterID, order.OrderNo); err != nil {
+		return 0, err
+	}
+	var listingConv model.ChatConversation
+	err = tx.Where("listing_id = ? AND type = ?", listing.ID, chat.ConversationTypeListingGroup).First(&listingConv).Error
+	if err == nil {
+		conversationID = listingConv.ID
+	} else if !errors.Is(err, gorm.ErrRecordNotFound) {
+		return 0, err
 	}
 
 	if isPlatformHandoffOrder(*order) {