feat(grouping): 新增分组功能并优化 Markdown 文件操作

- 新增分组实体、控制器、服务和映射器
- 实现分组创建、获取、更新和删除接口
- 优化 Markdown 文件创建、获取和删除接口- 新增全局异常处理和日志记录
- 更新数据库表结构和字段类型
- 重构前端页面，支持分组和 Markdown 文件展示

biji-houdaun/src/main/java/com/test/bijihoudaun/controller/GroupingController.java

@@ -0,0 +1,51 @@
+package com.test.bijihoudaun.controller;
+
+import com.test.bijihoudaun.entity.Grouping;
+import com.test.bijihoudaun.service.GroupingService;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@Tag(name = "分组接口")
+@RestController
+@RequestMapping("/api/groupings")
+public class GroupingController {
+
+    @Autowired
+    private GroupingService groupingService;
+
+    @Operation(summary = "创建分组")
+    @PostMapping
+    public ResponseEntity<Grouping> createGrouping(@RequestBody Grouping grouping) {
+        Grouping created = groupingService.createGrouping(grouping);
+        return ResponseEntity.ok(created);
+    }
+
+    @Operation(summary = "获取全部分组")
+    @GetMapping
+    public ResponseEntity<List<Grouping>> getAllGroupings() {
+        List<Grouping> groupings = groupingService.getAllGroupings();
+        return ResponseEntity.ok(groupings);
+    }
+
+    @Operation(summary = "更新分组名称")
+    @PutMapping("/{id}")
+    public ResponseEntity<Grouping> updateGrouping(
+            @PathVariable Long id, 
+            @RequestBody Grouping grouping) {
+        grouping.setId(id);
+        Grouping updated = groupingService.updateGrouping(grouping);
+        return ResponseEntity.ok(updated);
+    }
+
+    @Operation(summary = "删除分组")
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteGrouping(@PathVariable Long id) {
+        groupingService.deleteGrouping(id);
+        return ResponseEntity.noContent().build();
+    }
+}