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

public/assets/libs/eonasdan-bootstrap-datetimepicker/docs/theme/toc.html

@@ -0,0 +1,10 @@
+<div class="bs-sidebar hidden-print affix well" role="complementary">
+    <ul class="nav bs-sidenav">
+    {% for toc_item in toc %}
+        <li class="main {% if toc_item.active %}active{% endif %}"><a href="{{ toc_item.url }}">{{ toc_item.title }}</a></li>
+        {% for toc_item in toc_item.children %}
+            <li><a href="{{ toc_item.url }}">{{ toc_item.title }}</a></li>
+        {% endfor %}
+    {% endfor %}
+    </ul>
+</div>