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/index/view/common/sidenav.html

@@ -0,0 +1,12 @@
+<div class="sidebar-toggle"><i class="fa fa-bars"></i></div>
+<div class="sidenav" id="sidebar-nav">
+    {:hook('user_sidenav_before')}
+    <ul class="list-group">
+        <li class="list-group-heading">{:__('Member center')}</li>
+        <li class="list-group-item {:check_nav_active('user/index')}"> <a href="{:url('user/index')}"><i class="fa fa-user-circle fa-fw"></i> {:__('User center')}</a> </li>
+        <li class="list-group-item {:check_nav_active('user/profile')}"> <a href="{:url('user/profile')}"><i class="fa fa-user-o fa-fw"></i> {:__('Profile')}</a> </li>
+        <li class="list-group-item {:check_nav_active('user/changepwd')}"> <a href="{:url('user/changepwd')}"><i class="fa fa-key fa-fw"></i> {:__('Change password')}</a> </li>
+        <li class="list-group-item {:check_nav_active('user/logout')}"> <a href="{:url('user/logout')}"><i class="fa fa-sign-out fa-fw"></i> {:__('Sign out')}</a> </li>
+    </ul>
+    {:hook('user_sidenav_after')}
+</div>