feat(device): 新增设备定位查询接口并修复定位数据存储问题

- 新增 GET /{sn}/location 接口，支持网页端查询设备最新定位信息
- 新增 DeviceLocationVO 视图对象用于返回定位数据
- 在 LocationService 中实现 getLatestBySn 方法
- 修复 map_error 字段类型错误：从 INT 改为 VARCHAR(255)
- 修复移动端上报定位时 lastSuccessfulTime 缺失问题，由服务端统一写入

src/main/java/com/youlai/boot/device/controller/DeviceOpsController.java

@@ -7,9 +7,12 @@ import com.youlai.boot.common.result.Result;
 import com.youlai.boot.device.model.entity.SnDeviceInfo;
 import com.youlai.boot.device.model.form.AppActionForm;
 import com.youlai.boot.device.model.form.DeveloperForm;
+import com.youlai.boot.device.model.vo.DeviceLocationVO;
 import com.youlai.boot.device.model.vo.DevicePageVO;
 import com.youlai.boot.device.service.DeviceService;
+import com.youlai.boot.device.service.LocationService;
 import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.Parameter;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
@@ -30,6 +33,7 @@ import org.springframework.web.bind.annotation.*;
 public class DeviceOpsController {
 
     private final DeviceService deviceService;
+    private final LocationService locationService;
 
     @Operation(summary = "获取SN绑定激活信息")
     @GetMapping("/{sn}/info")
@@ -96,6 +100,13 @@ public class DeviceOpsController {
         return Result.judge(result);
     }
 
+    @Operation(summary = "获取设备最新定位信息", description = "返回设备最近一次上报的定位信息，用于网页端展示百度地图")
+    @GetMapping("/{sn}/location")
+    public Result<DeviceLocationVO> getLocation(@Parameter(description = "设备序列号", required = true) @PathVariable String sn) {
+        DeviceLocationVO location = locationService.getLatestBySn(sn);
+        return Result.success(location);
+    }
+
     @Operation(summary = "设备重置")
     @PostMapping("/restore")
     @Log(module = LogModuleEnum.DEVICE, value = ActionTypeEnum.RESTORE)