feat(mill): 添加清空指定机架所有备辊功能

- 在 MesRollStandbyController 中新增 clearByStand 接口
- 添加 DELETE /mill/standby/clear 路径用于清空指定机架备辊
- 实现同时回退轧辊状态的业务逻辑
- 添加权限校验 @PreAuthorize("@ss.hasPermi('mill:standby:remove')")
- 集成操作日志记录功能
- 更新 MesRollChangeServiceImpl 中的代码风格，统一 if 语句的大括号格式

ruoyi-mill/src/main/java/com/ruoyi/mill/controller/MesRollStandbyController.java

@@ -11,6 +11,7 @@ import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 import com.ruoyi.common.annotation.Log;
 import com.ruoyi.common.core.controller.BaseController;
@@ -101,4 +102,16 @@ public class MesRollStandbyController extends BaseController
     {
         return toAjax(mesRollStandbyService.deleteMesRollStandbyByStandbyIds(standbyIds));
     }
+
+    /**
+     * 清空指定机架所有备辊，同时回退轧辊状态
+     * DELETE /mill/standby/clear?lineId=xxx&standNo=1%23
+     */
+    @PreAuthorize("@ss.hasPermi('mill:standby:remove')")
+    @Log(title = "下批轧辊（待换上）", businessType = BusinessType.DELETE)
+    @DeleteMapping("/clear")
+    public AjaxResult clearByStand(@RequestParam Long lineId, @RequestParam String standNo)
+    {
+        return toAjax(mesRollStandbyService.clearByStand(lineId, standNo));
+    }
 }