feat(web): 会话头像/名称可点击展开详情栏，移除"关于 MeetingIM"设置页

聊天窗口头部的头像和昵称此前只是静态展示，只有右侧"i"图标能展开
详情栏；现在点击头像或名称同样会触发 onToggleDetail，单聊群聊均
生效。

按产品决定移除设置里的"关于 MeetingIM"页面（桌面目录、移动端"我的"
二级设置列表两处入口一并去掉），该页面唯一内容是版本号和一个后端
本就不支持 platform=web 的检查更新按钮，删除后 AboutPage.tsx 和
仅被它使用的 lib/api/app.ts 一并清理为死代码。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/lib/api/app.ts

@@ -1,20 +0,0 @@
-import { imGet } from './client';
-
-export interface AppRelease {
-  latest_version: string;
-  min_supported_version: string;
-  update_type: 'none' | 'optional' | 'required';
-  release_notes?: string;
-  store_url?: string;
-  package_url?: string;
-  checksum?: string;
-  published_at?: string;
-}
-
-/** docs/IM-前后端对接文档.md:2366-2367. `platform` here is `web`, matching this rewrite's own
- *  target -- not confirmed against a real response (the doc only shows ios/android in its own
- *  example), so `update_type` may come back differently for an unrecognized platform value. */
-export function getLatestRelease(currentVersion: string, platform: 'web' | 'ios' | 'android' = 'web') {
-  const qs = new URLSearchParams({ platform, current_version: currentVersion, channel: 'stable' });
-  return imGet<AppRelease>(`/app/releases/latest?${qs.toString()}`);
-}