revert: 移除转赠资产禁止兑换积分的限制

经数据核实，转赠后兑换积分属于合法行为（资产转赠后归接收方所有）。
并发漏洞虽然产生了重复转赠/发货记录，但实际经济损失为 0 元：
- 18 个重复发货资产中，没有任何一个真正被两方都发了货
- 没有任何资产被重复兑换积分

保留前两个并发修复（SELECT FOR UPDATE + RowsAffected 检查），
回退第三个业务限制（禁止转赠资产兑换积分）。

internal/service/user/address_share.go

@@ -112,27 +112,7 @@ func (s *service) SubmitAddressShare(ctx context.Context, shareToken string, nam
 
 	s.logger.Info("SubmitAddressShare: Processing", zap.Int64("invID", claims.InventoryID), zap.Int64("owner", claims.OwnerUserID))
 
-	// 1. 基本安全校验
-	cnt, err := s.readDB.ShippingRecords.WithContext(ctx).Where(
-		s.readDB.ShippingRecords.InventoryID.Eq(claims.InventoryID),
-		s.readDB.ShippingRecords.Status.Neq(5), // 排除已取消
-	).Count()
-	if err == nil && cnt > 0 {
-		s.logger.Warn("SubmitAddressShare: Already processed", zap.Int64("invID", claims.InventoryID))
-		return 0, fmt.Errorf("already_processed")
-	}
-
-	inv, err := s.readDB.UserInventory.WithContext(ctx).Where(s.readDB.UserInventory.ID.Eq(claims.InventoryID)).First()
-	if err != nil {
-		s.logger.Error("SubmitAddressShare: Inventory not found", zap.Int64("invID", claims.InventoryID), zap.Error(err))
-		return 0, err
-	}
-	if inv.Status != 1 {
-		s.logger.Warn("SubmitAddressShare: Inventory unavailable", zap.Int64("invID", claims.InventoryID), zap.Int32("status", inv.Status))
-		return 0, fmt.Errorf("inventory_unavailable")
-	}
-
-	// 2. 确定资产最终归属地 (实名转赠逻辑)
+	// 1. 确定资产最终归属地 (实名转赠逻辑)
 	targetUserID := claims.OwnerUserID
 	isTransfer := false
 	if submittedByUserID != nil && *submittedByUserID > 0 && *submittedByUserID != claims.OwnerUserID {
@@ -142,7 +122,33 @@ func (s *service) SubmitAddressShare(ctx context.Context, shareToken string, nam
 
 	var addrID int64
 	err = s.repo.GetDbW().Transaction(func(tx *gorm.DB) error {
-		// a. 创建收货地址 (归属于 targetUserID)
+		// a. 锁定资产行（SELECT FOR UPDATE 防止并发转赠）
+		var inv model.UserInventory
+		lockResult := tx.Raw("SELECT * FROM user_inventory WHERE id = ? FOR UPDATE", claims.InventoryID).Scan(&inv)
+		if lockResult.Error != nil {
+			s.logger.Error("SubmitAddressShare: Lock inventory failed", zap.Int64("invID", claims.InventoryID), zap.Error(lockResult.Error))
+			return lockResult.Error
+		}
+		if inv.ID == 0 {
+			s.logger.Warn("SubmitAddressShare: Inventory not found", zap.Int64("invID", claims.InventoryID))
+			return fmt.Errorf("inventory_unavailable")
+		}
+		if inv.Status != 1 {
+			s.logger.Warn("SubmitAddressShare: Inventory unavailable", zap.Int64("invID", claims.InventoryID), zap.Int32("status", inv.Status))
+			return fmt.Errorf("inventory_unavailable")
+		}
+
+		// b. 在事务内检查发货记录（使用写库，避免主从延迟）
+		var shipCnt int64
+		if err := tx.Raw("SELECT COUNT(*) FROM shipping_records WHERE inventory_id = ? AND status != 5", claims.InventoryID).Scan(&shipCnt).Error; err != nil {
+			return err
+		}
+		if shipCnt > 0 {
+			s.logger.Warn("SubmitAddressShare: Already processed", zap.Int64("invID", claims.InventoryID))
+			return fmt.Errorf("already_processed")
+		}
+
+		// c. 创建收货地址 (归属于 targetUserID)
 		arow := &model.UserAddresses{
 			UserID:    targetUserID,
 			Name:      name,
@@ -164,7 +170,7 @@ func (s *service) SubmitAddressShare(ctx context.Context, shareToken string, nam
 		}
 		addrID = arow.ID
 
-		// b. 资产状态更新及所有权转移
+		// d. 资产状态更新及所有权转移（检查 RowsAffected 防止并发写入）
 		if isTransfer {
 			// 记录转赠流水
 			transferLog := &model.UserInventoryTransfers{
@@ -178,28 +184,36 @@ func (s *service) SubmitAddressShare(ctx context.Context, shareToken string, nam
 			}
 
 			// 更新资产所属人
-			if err := tx.Table("user_inventory").Where("id = ? AND user_id = ? AND status = 1", claims.InventoryID, claims.OwnerUserID).
+			result := tx.Table("user_inventory").Where("id = ? AND user_id = ? AND status = 1", claims.InventoryID, claims.OwnerUserID).
 				Updates(map[string]interface{}{
 					"user_id":    targetUserID,
 					"status":     3,
 					"updated_at": time.Now(),
 					"remark":     fmt.Sprintf("transferred_from_%d|shipping_requested", claims.OwnerUserID),
-				}).Error; err != nil {
-				return err
+				})
+			if result.Error != nil {
+				return result.Error
+			}
+			if result.RowsAffected == 0 {
+				return fmt.Errorf("inventory_unavailable")
 			}
 		} else {
 			// 仅更新状态 (原主发货)
-			if err := tx.Table("user_inventory").Where("id = ? AND user_id = ? AND status = 1", claims.InventoryID, claims.OwnerUserID).
+			result := tx.Table("user_inventory").Where("id = ? AND user_id = ? AND status = 1", claims.InventoryID, claims.OwnerUserID).
 				Updates(map[string]interface{}{
 					"status":     3,
 					"updated_at": time.Now(),
 					"remark":     "shipping_requested_via_share",
-				}).Error; err != nil {
-				return err
+				})
+			if result.Error != nil {
+				return result.Error
+			}
+			if result.RowsAffected == 0 {
+				return fmt.Errorf("inventory_unavailable")
 			}
 		}
 
-		// c. 创建发货记录 (归属于 targetUserID)
+		// e. 创建发货记录 (归属于 targetUserID)
 		// 使用资产价值快照，确保价格与分解时一致
 		price := inv.ValueCents
 		if price <= 0 && inv.ProductID > 0 {
@@ -554,6 +568,7 @@ func (s *service) RedeemInventoryToPoints(ctx context.Context, userID int64, inv
 	if err != nil {
 		return 0, err
 	}
+
 	valueCents := inv.ValueCents
 	valueSource := inv.ValueSource
 	valueSnapshotAt := inv.ValueSnapshotAt