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

application/admin/lang/zh-cn/kefu/config.php

@@ -0,0 +1,25 @@
+<?php
+
+return [
+    'KeFu config'            => '客服配置',
+    'Chat name'              => '应用名称',
+    'Ecs Exit'               => '按ESC退出聊天窗口',
+    'Ecs Exit 0'             => '不开启',
+    'Ecs Exit 1'             => '开启',
+    'Send message Key'       => '发送消息按键',
+    'Send message Key 0'     => 'CTRL+回车键',
+    'Send message Key 1'     => '回车键',
+    'WebSocket port'         => 'WebSocket端口',
+    'Allow domain'           => '跨站调用允许域名',
+    'New user tip'           => '新用户一句话欢迎文案',
+    'New user msg'           => '新用户欢迎消息(默认)',
+    'Announcement'           => '会话窗口公告',
+    'Slider images'          => '会话窗口轮播图',
+    'Chat introduces'        => '会话窗口富文本',
+    'A line of one'          => '一行一个',
+    'Input status Tip'       => '实时显示消息输入状态',
+    'Input status display'   => '输入状态显示',
+    'Input status display 0' => '不显示',
+    'Input status display 1' => '显示',
+    'Input status display 2' => '仅客服显示',
+];