refactor: 移除 IoT 卡未使用的价格字段

- 移除 IotCard 模型的 cost_price 和 distribute_price 字段
- 移除 StandaloneIotCardResponse DTO 中对应的字段
- 添加数据库迁移文件 000066_remove_iot_card_price_fields
- 更新 opencode.json 配置

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

internal/service/iot_card/service.go

@@ -243,11 +243,9 @@ func (s *Service) toStandaloneResponse(card *model.IotCard, shopMap map[uint]str
 		CarrierName:           card.CarrierName,
 		IMSI:                  card.IMSI,
 		MSISDN:                card.MSISDN,
-		BatchNo:               card.BatchNo,
-		Supplier:              card.Supplier,
-		CostPrice:             card.CostPrice,
-		DistributePrice:       card.DistributePrice,
-		Status:                card.Status,
+		BatchNo:  card.BatchNo,
+		Supplier: card.Supplier,
+		Status:   card.Status,
 		ShopID:                card.ShopID,
 		ActivatedAt:           card.ActivatedAt,
 		ActivationStatus:      card.ActivationStatus,