fix(web): 隐藏文件助手入口，修复自聊天详情栏错误操作

后端目前没有支持文件助手所需的配额/分类等能力，只是把它当作
普通话题处理；与其做一个功能不全的界面，先从导航栏、会话列表
置顶区、通讯录固定入口、设置页移动端快捷入口中移除该入口。slf
话题现在按普通会话行为处理（排序、未读计数均不再特殊处理）。

同时修复 DetailColumn 对自聊天（slf）显示语音/视频通话、备注、
拉黑、举报、删除好友等对自己无意义操作的问题，改为仅显示适用
的发消息/查找聊天记录/置顶/免打扰/清空聊天记录等项。

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

web/src/app/NavRail.tsx

@@ -13,7 +13,6 @@ const TOP_ITEMS: NavRailItem[] = [
   { to: '/messages', icon: 'chat_bubble', label: '消息' },
   { to: '/contacts', icon: 'contacts', label: '通讯录' },
   { to: '/favorites', icon: 'inventory_2', label: '收藏' },
-  { to: '/files', icon: 'folder', label: '文件助手' },
 ];
 
 const BOTTOM_ITEMS: NavRailItem[] = [
@@ -21,14 +20,8 @@ const BOTTOM_ITEMS: NavRailItem[] = [
   { to: '/settings', icon: 'settings', label: '设置' },
 ];
 
-/** `/files` is `<Navigate to="/messages/slf" replace />` (App.tsx) -- the real URL right after
- *  clicking "文件助手" is `/messages/slf`, which a plain (non-`end`) NavLink match makes "消息"
- *  light up for (a same-topicId prefix match) while "文件助手" itself (`to: '/files'`, a path that
- *  no longer exists once redirected) never matches at all. Overriding both items' active state off
- *  the real pathname instead of trusting NavLink's own prefix match fixes both sides of the mix-up. */
 function isNavItemActive(to: string, pathname: string): boolean {
-  if (to === '/files') return pathname === '/messages/slf';
-  if (to === '/messages') return pathname.startsWith('/messages') && pathname !== '/messages/slf';
+  if (to === '/messages') return pathname.startsWith('/messages');
   return pathname === to || pathname.startsWith(`${to}/`);
 }
 
@@ -39,12 +32,9 @@ function NavRailButton({ item }: { item: NavRailItem }) {
     // Plain Link, not NavLink -- NavLink computes its OWN `aria-current` from ITS OWN prefix-match
     // logic unconditionally (confirmed by reading react-router's source: passing an `aria-current`
     // prop only changes the STRING used, not whether it's applied at all, which stays gated on
-    // NavLink's internal isActive). That's exactly `/files`'s own problem above -- NavLink's naive
-    // match would light up "消息" for `/messages/slf`, not "文件助手" -- so a second, independent
-    // aria-current computation fighting the same override this file already needed for `className`
-    // is a real, verifiable a11y bug (screen readers and sighted highlighting would disagree on
-    // which icon is current). Driving both off the one already-correct `isActive` avoids that
-    // entirely.
+    // NavLink's internal isActive), so a second, independent aria-current computation could in
+    // principle disagree with the `className` highlight computed by `isActive` below. Driving both
+    // off the one shared `isActive` value keeps them impossible to desync.
     <Link
       to={item.to}
       title={item.label}