feat(03.1-01): 建立设备实时 Gateway 调用链路，替换 mock 数据

- GetRealtimeStatus() device case 新增 Gateway sync-info 实时调用（IMEI/SN 优先，gatewayClient nil 安全）
- 新增 mapSyncRespToDeviceGatewayInfo() 将 SyncDeviceInfoResp 映射为 B 端 DeviceGatewayInfo DTO
- 新增 strPtr() 辅助函数（空字符串→nil，防止 JSON 出现大量空字符串字段）
- client_asset.go 删除 buildMockDeviceRealtime()，改为调用 assetService.GetRealtimeStatus() 获取真实数据
- 新增 mapDeviceGatewayInfoToClientInfo() 将 B 端 DeviceGatewayInfo 映射为 C 端 DeviceRealtimeInfo
- Gateway 调用失败时 DeviceRealtime 返回 null，不阻断主流程

internal/service/asset/service.go

@@ -300,6 +300,30 @@ func (s *Service) GetRealtimeStatus(ctx context.Context, assetType string, id ui
 		}
 		resp.DeviceProtectStatus = s.getDeviceProtectStatus(ctx, id)
 
+		// 实时查询 Gateway 设备状态（不缓存，per D-05）
+		// Gateway 失败不阻断主流程，DeviceRealtime 返回 null（per D-06）
+		if s.gatewayClient != nil {
+			device, devErr := s.deviceStore.GetByID(ctx, id)
+			if devErr == nil {
+				// IMEI 优先，无则用 SN（与 Refresh 中 updateDeviceFromSyncInfo 保持一致）
+				cardNo := device.IMEI
+				if cardNo == "" {
+					cardNo = device.SN
+				}
+				if cardNo != "" {
+					if syncResp, syncErr := s.gatewayClient.SyncDeviceInfo(ctx, &gateway.SyncDeviceInfoReq{
+						CardNo: cardNo,
+					}); syncErr == nil {
+						resp.DeviceRealtime = mapSyncRespToDeviceGatewayInfo(syncResp)
+					} else {
+						logger.GetAppLogger().Warn("GetRealtimeStatus: sync-info 调用失败，DeviceRealtime 返回 null",
+							zap.Uint("device_id", id),
+							zap.Error(syncErr))
+					}
+				}
+			}
+		}
+
 	default:
 		return nil, errors.New(errors.CodeInvalidParam, "不支持的资产类型，仅支持 card 或 device")
 	}
@@ -307,6 +331,57 @@ func (s *Service) GetRealtimeStatus(ctx context.Context, assetType string, id ui
 	return resp, nil
 }
 
+// mapSyncRespToDeviceGatewayInfo 将 Gateway SyncDeviceInfoResp 映射为 B 端 DeviceGatewayInfo DTO
+// 使用指针字段，未赋值的字段保持 nil（omitempty）
+func mapSyncRespToDeviceGatewayInfo(r *gateway.SyncDeviceInfoResp) *dto.DeviceGatewayInfo {
+	info := &dto.DeviceGatewayInfo{
+		OnlineStatus:    &r.OnlineStatus,
+		RunTime:         strPtr(r.RunTime),
+		ConnectTime:     strPtr(r.ConnectTime),
+		LastOnlineTime:  strPtr(r.LastOnlineTime),
+		LastUpdateTime:  strPtr(r.LastUpdateTime),
+		Rsrp:            &r.Rsrp,
+		Rsrq:            &r.Rsrq,
+		Rssi:            strPtr(r.RSSI),
+		Sinr:            &r.Sinr,
+		SSID:            strPtr(r.SSID),
+		WifiEnabled:     &r.WifiEnabled,
+		WifiPassword:    strPtr(r.WifiPassword),
+		IPAddress:       strPtr(r.IPAddress),
+		WANIP:           strPtr(r.WANIP),
+		LANIP:           strPtr(r.LANIP),
+		MACAddress:      strPtr(r.MacAddress),
+		DailyUsage:      strPtr(r.DailyUsage),
+		DLStats:         strPtr(r.DLStats),
+		ULStats:         strPtr(r.ULStats),
+		LimitSpeed:      &r.LimitSpeed,
+		CurrentIccid:    strPtr(r.CurrentIccid),
+		MaxClients:      &r.MaxClients,
+		SoftwareVersion: strPtr(r.SoftwareVersion),
+		SwitchMode:      strPtr(r.SwitchMode),
+		SyncInterval:    &r.SyncInterval,
+		DeviceID:        strPtr(r.DeviceID),
+		DeviceName:      strPtr(r.DeviceName),
+		DeviceType:      strPtr(r.DeviceType),
+		IMEI:            strPtr(r.IMEI),
+		IMSI:            strPtr(r.IMSI),
+		Status:          &r.Status,
+	}
+	if r.BatteryLevel != nil {
+		info.BatteryLevel = r.BatteryLevel
+	}
+	return info
+}
+
+// strPtr 将空字符串转为 nil，非空字符串返回指针
+// 避免 JSON 响应中出现大量空字符串字段（omitempty 对空字符串无效）
+func strPtr(s string) *string {
+	if s == "" {
+		return nil
+	}
+	return &s
+}
+
 // Refresh 刷新资产数据（调网关同步）
 func (s *Service) Refresh(ctx context.Context, assetType string, id uint) (*dto.AssetRealtimeStatusResponse, error) {
 	switch assetType {