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/iot_card_import/service.go

@@ -76,6 +76,7 @@ func (s *Service) CreateImportTask(ctx context.Context, req *dto.ImportIotCardRe
 		Status:      model.ImportTaskStatusPending,
 		CarrierID:   req.CarrierID,
 		CarrierType: carrier.CarrierType,
+		CarrierName: carrier.CarrierName,
 		BatchNo:     req.BatchNo,
 		FileName:    fileName,
 		StorageKey:  req.FileKey,
@@ -138,11 +139,9 @@ func (s *Service) List(ctx context.Context, req *dto.ListImportTaskRequest) (*dt
 		return nil, err
 	}
 
-	carrierMap := s.loadCarriers(ctx, tasks)
-
 	list := make([]*dto.ImportTaskResponse, 0, len(tasks))
 	for _, task := range tasks {
-		list = append(list, s.toTaskResponse(task, carrierMap))
+		list = append(list, s.toTaskResponse(task))
 	}
 
 	totalPages := int(total) / pageSize
@@ -165,14 +164,8 @@ func (s *Service) GetByID(ctx context.Context, id uint) (*dto.ImportTaskDetailRe
 		return nil, errors.New(errors.CodeNotFound, "导入任务不存在")
 	}
 
-	carrierMap := make(map[uint]string)
-	var carrier model.Carrier
-	if s.db.WithContext(ctx).First(&carrier, task.CarrierID).Error == nil {
-		carrierMap[carrier.ID] = carrier.CarrierName
-	}
-
 	resp := &dto.ImportTaskDetailResponse{
-		ImportTaskResponse: *s.toTaskResponse(task, carrierMap),
+		ImportTaskResponse: *s.toTaskResponse(task),
 		SkippedItems:       make([]*dto.ImportResultItemDTO, 0),
 		FailedItems:        make([]*dto.ImportResultItemDTO, 0),
 	}
@@ -198,28 +191,7 @@ func (s *Service) GetByID(ctx context.Context, id uint) (*dto.ImportTaskDetailRe
 	return resp, nil
 }
 
-func (s *Service) loadCarriers(ctx context.Context, tasks []*model.IotCardImportTask) map[uint]string {
-	carrierIDs := make([]uint, 0)
-	carrierIDSet := make(map[uint]bool)
-	for _, task := range tasks {
-		if task.CarrierID > 0 && !carrierIDSet[task.CarrierID] {
-			carrierIDs = append(carrierIDs, task.CarrierID)
-			carrierIDSet[task.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
-}
-
-func (s *Service) toTaskResponse(task *model.IotCardImportTask, carrierMap map[uint]string) *dto.ImportTaskResponse {
+func (s *Service) toTaskResponse(task *model.IotCardImportTask) *dto.ImportTaskResponse {
 	var startedAt, completedAt *time.Time
 	if task.StartedAt != nil {
 		startedAt = task.StartedAt
@@ -234,7 +206,8 @@ func (s *Service) toTaskResponse(task *model.IotCardImportTask, carrierMap map[u
 		Status:       task.Status,
 		StatusText:   getStatusText(task.Status),
 		CarrierID:    task.CarrierID,
-		CarrierName:  carrierMap[task.CarrierID],
+		CarrierType:  task.CarrierType,
+		CarrierName:  task.CarrierName,
 		BatchNo:      task.BatchNo,
 		FileName:     task.FileName,
 		TotalCount:   task.TotalCount,