实例顶栏增加退出登录按钮，便于清会话回到登录页。

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

lib/common/static/instance_theme.css

@@ -626,6 +626,39 @@ html[data-theme="light"] .theme-toggle-btn.is-active {
   margin-left: auto;
 }
 
+.instance-logout-btn {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  padding: 5px 12px;
+  font-size: 0.82rem;
+  line-height: 1.2;
+  color: var(--inst-muted, #9aa3b2);
+  background: transparent;
+  border: 1px solid rgba(255, 255, 255, 0.14);
+  border-radius: 8px;
+  text-decoration: none;
+  white-space: nowrap;
+  cursor: pointer;
+}
+
+.instance-logout-btn:hover {
+  color: var(--inst-text, #e8ecf4);
+  border-color: rgba(255, 255, 255, 0.28);
+  background: rgba(255, 255, 255, 0.04);
+}
+
+html[data-theme="light"] .instance-logout-btn {
+  color: #5b6472;
+  border-color: rgba(0, 0, 0, 0.12);
+}
+
+html[data-theme="light"] .instance-logout-btn:hover {
+  color: #1f2937;
+  border-color: rgba(0, 0, 0, 0.22);
+  background: rgba(0, 0, 0, 0.03);
+}
+
 .instance-header-toolbar-filter label {
   display: inline-flex;
   align-items: center;

lib/instance/templates/instance_header_panel.html

@@ -32,6 +32,9 @@
                 <span class="risk-status-badge risk-status-{{ risk_status.status|default('normal') }}" id="account-risk-badge" role="status" title="{{ risk_status.reason|default('', true) }}" data-status-label="{{ risk_status.status_label|default('正常') }}"{% if risk_status.freeze_until_ms %} data-freeze-until-ms="{{ risk_status.freeze_until_ms }}"{% endif %}>{{ risk_status.status_label|default('正常') }}</span>
             </div>
             {% include 'instance_theme_toggle.html' %}
+            {% if show_logout|default(true) %}
+            <a href="/logout" class="instance-logout-btn" title="退出登录">退出</a>
+            {% endif %}
         </div>
     </div>
     <div class="instance-header-stats-wrap instance-desktop-only">