feat(03.1-01): 修复静态 DTO 映射缺口

- toDeviceResponse() 补全 5 个 DB 缓存字段（OnlineStatus/LastOnlineTime/SoftwareVersion/SwitchMode/LastGatewaySyncAt）
- ListBindings() 补全 IsCurrent 字段映射
- buildDeviceResolveResponse() 补全 isCurrentMap + BoundCardInfo.IsCurrent + 5 个 DB 缓存字段
- GetRealtimeStatus() device case 补全 isCurrentMap + BoundCardInfo.IsCurrent

internal/service/device/binding.go

@@ -57,6 +57,7 @@ func (s *Service) ListBindings(ctx context.Context, deviceID uint) (*dto.ListDev
 			CarrierName:  card.CarrierName, // 直接使用 IotCard 的冗余字段
 			Status:       card.Status,
 			BindTime:     binding.BindTime,
+			IsCurrent:    binding.IsCurrent,
 		}
 		responses = append(responses, resp)
 	}