feat: WebUI 框架设置页面 + API Key 管理 UI

新增:
- static/web_panel/pages/settings.html — API Key CRUD 界面
- 侧边栏 '框架设置' 导航项 (齿轮图标)
- BUILTIN_PAGES 增加 'settings'
- UI 功能: 创建对话框(名称/权限/过期), 列表表格, 一键删除

权限模板:
- readonly — framework.status.read + plugin.info.read
- monitor — + framework.event.subscribe
- full — admin (全部)

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

static/web_panel/home.html

@@ -46,6 +46,10 @@
                 <svg width="20" height="20" viewBox="0 0 24 24"><path d="M20 6h-8l-2-2H4c-1.1 0-2 .9-2 2v12c0 1.1.9 2 2 2h16c1.1 0 2-.9 2-2V8c0-1.1-.9-2-2-2zm-1 4H5V8h14v2zm0 2v6H5v-6h14z"/></svg>
                 <span>文件管理</span>
             </a>
+            <a class="nav-item" data-page="settings">
+                <svg width="20" height="20" viewBox="0 0 24 24"><path d="M19.14 12.94c.04-.3.06-.61.06-.94 0-.32-.02-.64-.07-.94l2.03-1.58a.49.49 0 00.12-.61l-1.92-3.32a.49.49 0 00-.59-.22l-2.39.96c-.5-.38-1.03-.7-1.62-.94L14.4 2.81a.484.484 0 00-.41-.3h-3.98c-.2 0-.38.13-.45.32l-.36 2.54c-.59.24-1.13.57-1.62.94l-2.39-.96a.49.49 0 00-.59.22L2.74 8.87c-.12.21-.08.47.12.61l2.03 1.58c-.05.3-.07.62-.07.94s.02.64.07.94l-2.03 1.58a.49.49 0 00-.12.61l1.92 3.32c.12.22.37.29.59.22l2.39-.96c.5.38 1.03.7 1.62.94l.36 2.54c.05.19.24.31.44.31h3.98c.2 0 .38-.13.45-.32l.36-2.54c.59-.24 1.13-.56 1.62-.94l2.39.96c.22.08.47 0 .59-.22l1.92-3.32c.12-.22.07-.47-.12-.61l-2.01-1.58zM12 15.6c-1.98 0-3.6-1.62-3.6-3.6s1.62-3.6 3.6-3.6 3.6 1.62 3.6 3.6-1.62 3.6-3.6 3.6z"/></svg>
+                <span>框架设置</span>
+            </a>
 
             <!-- Plugin WebUI pages (collapsible) -->
             <div class="nav-expandable" id="nav-plugins">