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/exception/DbException.php

@@ -0,0 +1,43 @@
+<?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: 麦当苗儿 <zuojiazi@vip.qq.com> <http://zjzit.cn>
+// +----------------------------------------------------------------------
+
+namespace think\exception;
+
+use think\Exception;
+
+/**
+ * Database相关异常处理类
+ */
+class DbException extends Exception
+{
+    /**
+     * DbException constructor.
+     * @param string    $message
+     * @param array     $config
+     * @param string    $sql
+     * @param int       $code
+     */
+    public function __construct($message, array $config, $sql, $code = 10500)
+    {
+        $this->message = $message;
+        $this->code    = $code;
+
+        $this->setData('Database Status', [
+            'Error Code'    => $code,
+            'Error Message' => $message,
+            'Error SQL'     => $sql,
+        ]);
+
+        unset($config['username'], $config['password']);
+        $this->setData('Database Config', $config);
+    }
+
+}