refactor(module-llm):优化 DatasetController 中的文件下载逻辑

- 更新导入语句，增加必要的异常处理
- 修改 downloadExampleFile 方法，优化代码格式
- 调整 getFileInfo 方法，统一代码风格

yudao-module-llm/yudao-module-llm-biz/src/main/java/cn/iocoder/yudao/module/llm/controller/admin/dataset/DatasetController.java

@@ -23,7 +23,9 @@ import org.springframework.web.bind.annotation.*;
 import javax.annotation.Resource;
 import javax.servlet.http.HttpServletResponse;
 import javax.validation.Valid;
-import java.io.*;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
 import java.net.URLEncoder;
 import java.util.List;
 
@@ -102,7 +104,7 @@ public class DatasetController {
 
     @GetMapping("/download-example")
     @Operation(summary = "下载示例文件")
-    public ResponseEntity<InputStreamResource> downloadExampleFile(@RequestParam("type") int type, HttpServletResponse response) throws IOException {
+    public ResponseEntity<InputStreamResource> downloadExampleFile (@RequestParam("type") int type, HttpServletResponse response) throws IOException {
         FileInfoVO fileInfo = getFileInfo(type);
 
         // 从 resources/file/dataset_example 目录加载文件
@@ -121,7 +123,7 @@ public class DatasetController {
                 .body(new InputStreamResource(inputStream));
     }
 
-    private FileInfoVO getFileInfo(int type) {
+    private FileInfoVO getFileInfo (int type) {
         switch (type) {
             case 1:
                 return new FileInfoVO("dataset_example_txt.txt", "text/plain");