feat: 实现运营商模块重构，添加冗余字段优化查询性能

主要变更：
- 新增 Carrier CRUD API（创建、列表、详情、更新、删除、状态更新）
- IotCard/IotCardImportTask 添加 carrier_type/carrier_name 冗余字段
- 移除 Carrier 表的 channel_name/channel_code 字段
- 查询时直接使用冗余字段，避免 JOIN Carrier 表
- 添加数据库迁移脚本（000021-000023）
- 添加单元测试和集成测试
- 同步更新 OpenAPI 文档和 specs

internal/service/device/binding.go

@@ -41,8 +41,6 @@ func (s *Service) ListBindings(ctx context.Context, deviceID uint) (*dto.ListDev
 		cardMap[card.ID] = card
 	}
 
-	carrierMap := s.loadCarrierData(ctx, cards)
-
 	responses := make([]*dto.DeviceCardBindingResponse, 0, len(bindings))
 	for _, binding := range bindings {
 		card := cardMap[binding.IotCardID]
@@ -56,7 +54,7 @@ func (s *Service) ListBindings(ctx context.Context, deviceID uint) (*dto.ListDev
 			IotCardID:    binding.IotCardID,
 			ICCID:        card.ICCID,
 			MSISDN:       card.MSISDN,
-			CarrierName:  carrierMap[card.CarrierID],
+			CarrierName:  card.CarrierName, // 直接使用 IotCard 的冗余字段
 			Status:       card.Status,
 			BindTime:     binding.BindTime,
 		}
@@ -147,26 +145,3 @@ func (s *Service) UnbindCard(ctx context.Context, deviceID uint, cardID uint) (*
 		Message: "解绑成功",
 	}, nil
 }
-
-func (s *Service) loadCarrierData(ctx context.Context, cards []*model.IotCard) map[uint]string {
-	carrierIDs := make([]uint, 0)
-	carrierIDSet := make(map[uint]bool)
-
-	for _, card := range cards {
-		if card.CarrierID > 0 && !carrierIDSet[card.CarrierID] {
-			carrierIDs = append(carrierIDs, card.CarrierID)
-			carrierIDSet[card.CarrierID] = true
-		}
-	}
-
-	carrierMap := make(map[uint]string)
-	if len(carrierIDs) > 0 {
-		var carriers []model.Carrier
-		s.db.WithContext(ctx).Where("id IN ?", carrierIDs).Find(&carriers)
-		for _, c := range carriers {
-			carrierMap[c.ID] = c.CarrierName
-		}
-	}
-
-	return carrierMap
-}