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/service.go

@@ -88,11 +88,11 @@ func (s *Service) ListStandalone(ctx context.Context, req *dto.ListStandaloneIot
 		return nil, err
 	}
 
-	carrierMap, shopMap := s.loadRelatedData(ctx, cards)
+	shopMap := s.loadShopNames(ctx, cards)
 
 	list := make([]*dto.StandaloneIotCardResponse, 0, len(cards))
 	for _, card := range cards {
-		item := s.toStandaloneResponse(card, carrierMap, shopMap)
+		item := s.toStandaloneResponse(card, shopMap)
 		list = append(list, item)
 	}
 
@@ -120,40 +120,25 @@ func (s *Service) GetByICCID(ctx context.Context, iccid string) (*dto.IotCardDet
 		return nil, err
 	}
 
-	carrierMap, shopMap := s.loadRelatedData(ctx, []*model.IotCard{card})
-	standaloneResp := s.toStandaloneResponse(card, carrierMap, shopMap)
+	shopMap := s.loadShopNames(ctx, []*model.IotCard{card})
+	standaloneResp := s.toStandaloneResponse(card, shopMap)
 
 	return &dto.IotCardDetailResponse{
 		StandaloneIotCardResponse: *standaloneResp,
 	}, nil
 }
 
-func (s *Service) loadRelatedData(ctx context.Context, cards []*model.IotCard) (map[uint]string, map[uint]string) {
-	carrierIDs := make([]uint, 0)
+func (s *Service) loadShopNames(ctx context.Context, cards []*model.IotCard) map[uint]string {
 	shopIDs := make([]uint, 0)
-	carrierIDSet := make(map[uint]bool)
 	shopIDSet := make(map[uint]bool)
 
 	for _, card := range cards {
-		if card.CarrierID > 0 && !carrierIDSet[card.CarrierID] {
-			carrierIDs = append(carrierIDs, card.CarrierID)
-			carrierIDSet[card.CarrierID] = true
-		}
 		if card.ShopID != nil && *card.ShopID > 0 && !shopIDSet[*card.ShopID] {
 			shopIDs = append(shopIDs, *card.ShopID)
 			shopIDSet[*card.ShopID] = 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
-		}
-	}
-
 	shopMap := make(map[uint]string)
 	if len(shopIDs) > 0 {
 		var shops []model.Shop
@@ -163,17 +148,18 @@ func (s *Service) loadRelatedData(ctx context.Context, cards []*model.IotCard) (
 		}
 	}
 
-	return carrierMap, shopMap
+	return shopMap
 }
 
-func (s *Service) toStandaloneResponse(card *model.IotCard, carrierMap map[uint]string, shopMap map[uint]string) *dto.StandaloneIotCardResponse {
+func (s *Service) toStandaloneResponse(card *model.IotCard, shopMap map[uint]string) *dto.StandaloneIotCardResponse {
 	resp := &dto.StandaloneIotCardResponse{
 		ID:               card.ID,
 		ICCID:            card.ICCID,
 		CardType:         card.CardType,
 		CardCategory:     card.CardCategory,
 		CarrierID:        card.CarrierID,
-		CarrierName:      carrierMap[card.CarrierID],
+		CarrierType:      card.CarrierType,
+		CarrierName:      card.CarrierName,
 		IMSI:             card.IMSI,
 		MSISDN:           card.MSISDN,
 		BatchNo:          card.BatchNo,