feat: 初始化进销存数据开放平台项目

初始化完整的前后端项目结构，包含ThinkPHP后端API服务和Next.js前端管理系统，添加基础配置、中间件、模型、路由等核心代码，以及项目文档和静态资源。

thinkphp/public/index.php

@@ -0,0 +1,24 @@
+<?php
+// +----------------------------------------------------------------------
+// | ThinkPHP [ WE CAN DO IT JUST THINK ]
+// +----------------------------------------------------------------------
+// | Copyright (c) 2006-2019 http://thinkphp.cn All rights reserved.
+// +----------------------------------------------------------------------
+// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
+// +----------------------------------------------------------------------
+// | Author: liu21st <liu21st@gmail.com>
+// +----------------------------------------------------------------------
+
+// [ 应用入口文件 ]
+namespace think;
+
+require __DIR__ . '/../vendor/autoload.php';
+
+// 执行HTTP应用并响应
+$http = (new App())->http;
+
+$response = $http->run();
+
+$response->send();
+
+$http->end($response);