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/console/output/driver/Buffer.php

@@ -0,0 +1,52 @@
+<?php
+// +----------------------------------------------------------------------
+// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]
+// +----------------------------------------------------------------------
+// | Copyright (c) 2006-2016 http://thinkphp.cn All rights reserved.
+// +----------------------------------------------------------------------
+// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
+// +----------------------------------------------------------------------
+// | Author: yunwuxin <448901948@qq.com>
+// +----------------------------------------------------------------------
+
+namespace think\console\output\driver;
+
+use think\console\Output;
+
+class Buffer
+{
+    /**
+     * @var string
+     */
+    private $buffer = '';
+
+    public function __construct(Output $output)
+    {
+        // do nothing
+    }
+
+    public function fetch()
+    {
+        $content      = $this->buffer;
+        $this->buffer = '';
+        return $content;
+    }
+
+    public function write($messages, $newline = false, $options = Output::OUTPUT_NORMAL)
+    {
+        $messages = (array) $messages;
+
+        foreach ($messages as $message) {
+            $this->buffer .= $message;
+        }
+        if ($newline) {
+            $this->buffer .= "\n";
+        }
+    }
+
+    public function renderException(\Exception $e)
+    {
+        // do nothing
+    }
+
+}