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/features/contacts/ContactsListColumn.tsx

@@ -12,7 +12,6 @@ import { getBlocks, getFriendRequests, getFriends } from '@/lib/api/friends';
 const FIXED_ENTRIES = [
   { key: 'requests', route: '/contacts/requests', icon: 'person_add', label: '新朋友', colorClass: 'bg-warn-bg text-warn' },
   { key: 'groups', route: '/contacts/groups', icon: 'groups', label: '群聊', colorClass: 'bg-accent-soft-bg text-accent' },
-  { key: 'files', route: '/files', icon: 'folder', label: '文件助手', colorClass: 'bg-success-bg text-success' },
   { key: 'blocklist', route: '/contacts/blocklist', icon: 'block', label: '黑名单', colorClass: 'bg-[#f3efff] text-[#7c5cf6]' },
   // README §5.7: mobile-only -- desktop already reaches this via ChatList's own pinned row (§2.1),
   // §5.1's desktop entry list doesn't include it.
@@ -27,7 +26,8 @@ function groupInitial(name: string, initial: string | undefined): string {
 }
 
 /**
- * README §5.1 (320px): search + 4 fixed entries (新朋友/群聊/文件助手/黑名单) + letter-grouped
+ * README §5.1 (320px): search + fixed entries (新朋友/群聊/黑名单, 文件助手 removed -- see
+ * ChatListColumn.tsx's PINNED_ENTRIES doc comment for why) + letter-grouped
  * friend list + a right-side letter index. Friend list is fetched once (fetchAllPages) and both
  * grouped and searched client-side, same convention ChatListColumn already uses for conversations
  * -- friend lists are the same small-to-medium scale, no reason to hit the server per keystroke.