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/bootstrap-select/docs/custom_theme/nav.html

@@ -0,0 +1,60 @@
+<div class="navbar navbar-default navbar-fixed-top" role="navigation">
+  <div class="container">
+
+    <!-- Collapsed navigation -->
+    <div class="navbar-header">
+      {% if include_nav or include_next_prev or repo_url %}
+      <!-- Expander button -->
+      <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
+        <span class="sr-only">Toggle navigation</span>
+        <span class="icon-bar"></span>
+        <span class="icon-bar"></span>
+        <span class="icon-bar"></span>
+      </button>
+      {% endif %}
+
+      <!-- Main title -->
+      <a class="navbar-brand" href="{{ homepage_url }}">{{ site_name }}</a>
+    </div>
+
+    <!-- Expanded navigation -->
+    <div class="navbar-collapse collapse">
+      {% if include_nav %}
+      <!-- Main navigation -->
+      <ul class="nav navbar-nav">
+        {% for nav_item in nav %}
+        {% if nav_item.children %}
+        <li class="dropdown{% if nav_item.active %} active{% endif %}">
+          <a href="#" class="dropdown-toggle" data-toggle="dropdown">{{ nav_item.title }} <b class="caret"></b></a>
+          <ul class="dropdown-menu">
+            {% for nav_item in nav_item.children %}
+            {% include "nav-sub.html" %}
+            {% endfor %}
+          </ul>
+        </li>
+        {% else %}
+        <li {% if nav_item.active %}class="active"{% endif %}>
+          <a href="{{ nav_item.url }}">{{ nav_item.title }}</a>
+        </li>
+        {% endif %}
+        {% endfor %}
+      </ul>
+      {% endif %}
+
+      <ul class="nav navbar-nav navbar-right">
+        {% if repo_url %}
+        <li>
+          <a href="{{ repo_url }}">
+            {% if repo_name == 'GitHub' %}
+            <i class="fa fa-github"></i>
+            {% elif repo_name == 'Bitbucket' %}
+            <i class="fa fa-bitbucket"></i>
+            {% endif %}
+            {{ repo_name }}
+          </a>
+        </li>
+        {% endif %}
+      </ul>
+    </div>
+  </div>
+</div>