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/model/Pivot.php

@@ -0,0 +1,42 @@
+<?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\model;
+
+use think\Model;
+
+class Pivot extends Model
+{
+
+    /** @var Model */
+    public $parent;
+
+    protected $autoWriteTimestamp = false;
+
+    /**
+     * 架构函数
+     * @access public
+     * @param array|object  $data 数据
+     * @param Model         $parent 上级模型
+     * @param string        $table 中间数据表名
+     */
+    public function __construct($data = [], Model $parent = null, $table = '')
+    {
+        $this->parent = $parent;
+
+        if (is_null($this->name)) {
+            $this->name = $table;
+        }
+
+        parent::__construct($data);
+    }
+
+}