feat(api): 新增分类查询接口（列表+详情，支持树形结构）

AGENTS.md

@@ -15,7 +15,7 @@ ulthon_information/
 ├── app/                    # 应用核心(多应用模式)
 │   ├── admin/controller/   # 后台管理(15个控制器)
 │   ├── index/controller/   # 前台展示(5个控制器)
-│   ├── api/controller/     # API接口(微信/文件/验证码)
+│   ├── api/controller/     # API接口(文章/附件/分类/文件/验证码/密钥)
 │   ├── model/              # 全局模型(17个，非各应用内)
 │   ├── common/             # 跨应用共享层(tools/traits/model)
 │   └── middleware/          # 中间件(ConfigInit/AdminLog/PermissionRecord)
@@ -56,7 +56,7 @@ ulthon_information/
 app\BaseController (abstract: validate/success/error/redirect)
   +-- admin\controller\Common (Session鉴权) -> 15个子控制器
   +-- index\controller\BaseController (域名跳转/HTTPS) -> Common -> 3个子控制器
-  +-- api\controller\* (直接继承 BaseController) -> 3个控制器
+  +-- api\controller\* (直接继承 BaseController, ApiKeyAuth中间件) -> 7个控制器(含分类查询)
 ```
 
 ### 响应格式

app/api/controller/Categories.php

@@ -0,0 +1,91 @@
+<?php
+
+namespace app\api\controller;
+
+use app\BaseController;
+use app\model\Category;
+use app\middleware\ApiKeyAuth;
+
+class Categories extends BaseController
+{
+    protected $middleware = [ApiKeyAuth::class];
+
+    /**
+     * 分类列表
+     */
+    public function index()
+    {
+        $page = $this->request->param('page', 1, 'intval');
+        $limit = $this->request->param('limit', 15, 'intval');
+        $type = $this->request->param('type', '');
+        $pid = $this->request->param('pid', '', 'intval');
+        $tree = $this->request->param('tree', 0, 'intval');
+
+        $status_param = $this->request->param('status');
+        $status = is_null($status_param) ? 1 : $status_param;
+
+        if ($limit < 1) {
+            $limit = 1;
+        }
+        if ($limit > 100) {
+            $limit = 100;
+        }
+
+        $query = Category::where('delete_time', 0);
+
+        if ($status !== '') {
+            $query->where('status', $status);
+        }
+
+        if (!empty($type)) {
+            $query->where('type', $type);
+        }
+
+        if ($pid !== '') {
+            $query->where('pid', $pid);
+        }
+
+        $query->order('sort asc');
+
+        if ($tree) {
+            $list = $query->select()->toArray();
+            $treeList = array2level($list, 0, 0);
+
+            return json_message(['list' => $treeList]);
+        }
+
+        $list = $query->paginate([
+            'page' => $page,
+            'list_rows' => $limit,
+        ]);
+
+        return json_message([
+            'list' => $list->items(),
+            'total' => $list->total(),
+            'page' => $page,
+        ]);
+    }
+
+    /**
+     * 分类详情
+     */
+    public function read()
+    {
+        $id = $this->request->param('id', 0, 'intval');
+        if ($id <= 0) {
+            return json_message('参数错误');
+        }
+
+        $category = Category::where('delete_time', 0)
+            ->where('id', $id)
+            ->find();
+
+        if (empty($category)) {
+            return json_message('分类不存在');
+        }
+
+        $category->append(['model_parent', 'model_siblings']);
+
+        return json_message($category);
+    }
+}