交易记录改为顶部Tab切换，统一系统管理样式

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ft-app/app/templates/base.html

@@ -206,20 +206,9 @@
     <a href="/positions/" class="{% if active_nav == 'positions' %}active{% endif %}">
       <span class="icon">📐</span> 仓位管理
     </a>
-    <div class="nav-group{% if active_nav == 'trades' %} open{% endif %}" id="nav-trades">
-      <a class="nav-parent{% if active_nav == 'trades' %} active{% endif %}" onclick="toggleNavGroup(event, 'nav-trades')" href="#">
-        <span class="icon">📝</span> 交易记录
-        <span class="nav-arrow">▼</span>
-      </a>
-      <div class="nav-children">
-        <a href="/trades/" class="{% if active_nav == 'trades' and not request.query_params.get('view') %}active{% endif %}">
-          <span class="icon">📋</span> 持仓
-        </a>
-        <a href="/trades/?view=closed" class="{% if request.query_params.get('view') == 'closed' %}active{% endif %}">
-          <span class="icon">📊</span> 已平仓
-        </a>
-      </div>
-    </div>
+    <a href="/trades/" class="{% if active_nav == 'trades' %}active{% endif %}">
+      <span class="icon">📝</span> 交易记录
+    </a>
     <a href="/admin/" class="{% if active_nav == 'admin' %}active{% endif %}">
       <span class="icon">⚙️</span> 系统管理
     </a>