fix: pricing页面导航栏动态显示用户状态

- 登录用户显示：首页/会员套餐/翻译历史 + 用户名/退出
- 未登录用户显示：首页/会员套餐 + 登录/注册
- 添加navbar-toggler支持移动端展开

templates/pricing.html

@@ -12,9 +12,26 @@
     <nav class="navbar navbar-expand-lg navbar-dark bg-primary">
         <div class="container">
             <a class="navbar-brand" href="/">📄 PDF翻译助手</a>
-            <div class="navbar-nav ms-auto">
-                <a class="nav-link" href="/">首页</a>
-                <a class="nav-link" href="/login">登录</a>
+            <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav">
+                <span class="navbar-toggler-icon"></span>
+            </button>
+            <div class="collapse navbar-collapse" id="navbarNav">
+                <ul class="navbar-nav me-auto">
+                    <li class="nav-item"><a class="nav-link" href="/">首页</a></li>
+                    <li class="nav-item"><a class="nav-link active" href="/pricing">会员套餐</a></li>
+                    {% if user %}
+                    <li class="nav-item"><a class="nav-link" href="/history">翻译历史</a></li>
+                    {% endif %}
+                </ul>
+                <div class="navbar-nav">
+                    {% if user %}
+                    <span class="nav-link text-light">👋 {{ user.username }}</span>
+                    <a class="nav-link" href="/logout">退出</a>
+                    {% else %}
+                    <a class="nav-link" href="/login">登录</a>
+                    <a class="nav-link" href="/register">注册</a>
+                    {% endif %}
+                </div>
             </div>
         </div>
     </nav>