feat(file): 新增文件上传校验与错误码

- 支持图片格式与大小限制（最大5MB）
- 补充 FILE_NAME_ERROR、FILE_TYPE_ERROR、FILE_SIZE_EXCEED 错误码
- 移除 FileController.upload 的异常声明，统一由 BusinessException 处理

src/main/java/com/yolo/keyborad/controller/FileController.java

@@ -2,7 +2,6 @@ package com.yolo.keyborad.controller;
 
 import com.yolo.keyborad.common.BaseResponse;
 import com.yolo.keyborad.common.ResultUtils;
-import com.yolo.keyborad.model.dto.AppleLoginReq;
 import com.yolo.keyborad.service.FileService;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.Parameter;
@@ -12,8 +11,6 @@ import lombok.extern.slf4j.Slf4j;
 import org.springframework.web.bind.annotation.*;
 import org.springframework.web.multipart.MultipartFile;
 
-import java.io.File;
-
 /*
  * @author: ziin
  * @date: 2025/12/2 15:46
@@ -31,7 +28,7 @@ public class FileController {
     @PostMapping("/upload")
     @Operation(summary = "上传文件", description = "上传文件接口")
     @Parameter(name = "file",required = true,description = "上传的文件")
-    public BaseResponse<String> upload(@RequestParam("file") MultipartFile file) throws Exception {
+    public BaseResponse<String> upload(@RequestParam("file") MultipartFile file){
         String fileUrl = fileService.upload(file);
         return ResultUtils.success(fileUrl);
     }