refactor: restructure API authentication system and remove legacy files

- Updated API routes to use a unified versioning scheme under `/api/v1/auth`.
- Implemented new authentication controller for login, registration, and token management.
- Removed legacy user and index controllers, along with associated models and validation files.
- Updated documentation to reflect new API endpoints and usage.
- Cleaned up unused service and middleware files to streamline the application structure.

test_api.sh

@@ -26,8 +26,9 @@ echo "2. 启动开发服务器："
 echo "   php think run"
 echo ""
 echo "3. 访问测试接口："
-echo "   - 首页: http://localhost:8000/api/index"
-echo "   - 健康检查: http://localhost:8000/api/health"
+echo "   - 登录: POST http://localhost:8000/api/v1/auth/login"
+echo "   - 注册: POST http://localhost:8000/api/v1/auth/register"
+echo "   - 刷新 Token: POST http://localhost:8000/api/v1/auth/refresh"
 echo ""
 echo "4. 查看完整文档："
 echo "   cat README_API.md"