feat: 后端全量更新 - 含所有本次需求

- Contract.php: 返回合约账户余额(balance_contract)
- My.php: 地址管理增加BTC/ETH
- AppContract.php: 一键平仓(closeall)
- AppProxy.php: 代理专属注册链接 + 分级权限(L1/L2)
- site.php: 手续费减半(0.018→0.009)
- agent_permission_setup.sql: 代理权限SQL
- crypto_news_crawler.py: 新闻自动采集脚本

thinkphp/library/think/Env.php

@@ -0,0 +1,39 @@
+<?php
+// +----------------------------------------------------------------------
+// | ThinkPHP [ WE CAN DO IT JUST THINK ]
+// +----------------------------------------------------------------------
+// | Copyright (c) 2006~2018 http://thinkphp.cn All rights reserved.
+// +----------------------------------------------------------------------
+// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
+// +----------------------------------------------------------------------
+// | Author: liu21st <liu21st@gmail.com>
+// +----------------------------------------------------------------------
+
+namespace think;
+
+class Env
+{
+    /**
+     * 获取环境变量值
+     * @access public
+     * @param  string $name    环境变量名（支持二级 . 号分割）
+     * @param  string $default 默认值
+     * @return mixed
+     */
+    public static function get($name, $default = null)
+    {
+        $result = getenv(ENV_PREFIX . strtoupper(str_replace('.', '_', $name)));
+
+        if (false !== $result) {
+            if ('false' === $result) {
+                $result = false;
+            } elseif ('true' === $result) {
+                $result = true;
+            }
+
+            return $result;
+        }
+
+        return $default;
+    }
+}