Add logout control and show a single locked underlying on hedge select.

Nav gains an exit link when auth is enabled; PO option picker no longer shows unused ETH/BTC toggles.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/instance/templates/index.html

@@ -18,8 +18,8 @@
     <link rel="apple-touch-icon" href="/static/icons/apple-touch-icon.png">
     <link rel="manifest" href="/static/icons/manifest.webmanifest">
     <title>{{ pwa_app_name }}</title>
-    <link rel="stylesheet" href="/static/instance_page.css?v=27">
-    <link rel="stylesheet" href="/static/instance_theme.css?v=123">
+    <link rel="stylesheet" href="/static/instance_page.css?v=28">
+    <link rel="stylesheet" href="/static/instance_theme.css?v=124">
 
 </head>
 <body
@@ -152,6 +152,9 @@
 <div class="container">
     {% include 'instance_brand_header.html' %}
     <div class="top-nav">
+        {% if not auth_disabled %}
+        <a href="/logout" class="top-nav-logout" title="退出登录">退出</a>
+        {% endif %}
         <div class="top-nav-links">
         {% if hedge_plan_nav_visible and display.show_nav_hedge_plan %}
         <a href="/hedge-plan" class="{% if page == 'hedge_plan' %}active{% endif %}">{% if hedge_plan_show_options_options %}期期对冲{% else %}永期对冲{% endif %}</a>