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

addons/kefu/controller/Base.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace addons\kefu\controller;
+
+use think\addons\Controller;
+use think\Request;
+
+class Base extends Controller
+{
+
+    public function __construct(Request $request = null)
+    {
+        parent::__construct($request);
+        $config = get_addon_config('kefu');
+        // 设定主题模板目录
+        $this->view->engine->config('view_path', $this->view->engine->config('view_path') . trim($config['theme']) . DS);
+    }
+
+    protected function _initialize()
+    {
+        parent::_initialize();
+    }
+
+}