refactor: fix directory structure and namespaces for webman conventions

- Rename directories to lowercase: Controller→controller, Model→model, Service→service, Util→util, Bootstrap→bootstrap
- Update all namespaces from App\Xxx to app\xxx (webman convention)
- Update all import statements across the codebase
- Update route.php to use lowercase namespaces
- Remove unused CompanyFeishuApp model
- Comment out unimplemented controller routes

Following webman 2.x framework conventions:
- Models: app\model\{ClassName}
- Controllers: app\controller\{ClassName}
- Services: app\service\{ClassName}
- Utils: app\util\{ClassName}
- Middleware: app\middleware\{ClassName}

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/controller/AuthController.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace app\controller;
+
+use app\util\JwtUtil;
+use Webman\Http\Request;
+use Webman\Http\Response;
+
+class AuthController extends BaseController
+{
+    /**
+     * 用户登录
+     */
+    public function login(Request $request): Response
+    {
+        $username = $request->post('username');
+        $password = $request->post('password');
+
+        // TODO: 实现真实的登录逻辑
+        if (!$username || !$password) {
+            return $this->error('用户名或密码不能空');
+        }
+
+        // 模拟用户数据
+        $user = [
+            'user_id' => 1,
+            'username' => $username,
+            'name' => '测试用户',
+            'company_id' => 1,
+        ];
+
+        $token = JwtUtil::encode($user);
+
+        return $this->success([
+            'token' => $token,
+            'user' => $user,
+        ]);
+    }
+
+    /**
+     * 飞书免登
+     */
+    public function feishuLogin(Request $request): Response
+    {
+        $authCode = $request->post('auth_code');
+        $tenantKey = $request->post('tenant_key');
+
+        // TODO: 实现飞书免登逻辑
+        // 1. 根据 tenant_key 获取公司配置
+        // 2. 使用 auth_code 换取用户信息
+        // 3. 创建或更新用户
+        // 4. 生成 JWT Token
+
+        return $this->success([
+            'token' => JwtUtil::encode(['user_id' => 1, 'company_id' => 1]),
+            'user' => ['id' => 1, 'name' => '飞书用户', 'company_id' => 1],
+        ]);
+    }
+}