fix(web): 左上角自己头像接入真实数据，会话订阅失败不再静默吞错

NavRail 的自己头像此前是硬编码的"我"字，AppShell 从没往下传过真实的
user_id/nickname/avatar_file_id，所以无论是谁登录、有没有上传头像都不会变；
现在改为拉取 /v1/im/me 并用 Avatar 组件渲染，和设置页/联系人等处一致。

ConversationView 打开会话失败时原来是 .catch(() => {}) 整个吞掉，用户会看到
空白的消息列表且没有任何提示；由于已读回执只在拿到消息后才会发，未读角标
也会因此永久卡住。现在失败会弹出错误提示，不再静默。

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

web/src/app/AppShell.tsx

@@ -1,9 +1,11 @@
 import { useEffect } from 'react';
 
+import { useQuery } from '@tanstack/react-query';
 import { Outlet } from 'react-router-dom';
 
 import { CallRoot } from '@/features/calls/CallRoot';
 import { useBootstrap } from '@/lib/api/hooks';
+import { getMe } from '@/lib/api/profile';
 import { useChatList } from '@/lib/tinode/hooks';
 import { initCallSignaling } from '@/stores/calls';
 
@@ -19,6 +21,12 @@ import { NavRail } from './NavRail';
 export function AppShell() {
   const contacts = useChatList();
   const bootstrap = useBootstrap();
+  // Same `['me']` query SettingsLayout already runs -- sharing the key means whichever mounts
+  // first fetches it and the other just reads the cache, not two redundant requests. This was
+  // never wired up here before, so the rail's self-tile (NavRail below) had no avatar/name data
+  // at all and fell back to a permanently-hardcoded "我" glyph regardless of who was logged in or
+  // what avatar they'd uploaded -- see Avatar.tsx's own comment for the wider version of this gap.
+  const meQuery = useQuery({ queryKey: ['me'], queryFn: getMe });
   // Once per app session, regardless of which page is open -- an incoming call must surface even
   // while browsing contacts/settings/etc, not only while a conversation happens to be open.
   useEffect(() => {
@@ -37,7 +45,12 @@ export function AppShell() {
   return (
     <div className="flex h-dvh w-full overflow-hidden bg-surface-page">
       <div className="hidden sm:flex sm:h-full">
-        <NavRail unreadMessages={unreadMessages} />
+        <NavRail
+          unreadMessages={unreadMessages}
+          selfId={meQuery.data?.user_id}
+          selfName={meQuery.data?.profile.nickname || '我'}
+          selfAvatarFileId={meQuery.data?.profile.avatar_file_id}
+        />
       </div>
       <div className="flex min-w-0 flex-1 flex-col overflow-hidden">
         <div className="min-h-0 flex-1 overflow-hidden">

web/src/app/NavRail.tsx

@@ -1,5 +1,6 @@
 import { Link, useLocation } from 'react-router-dom';
 
+import { Avatar } from './Avatar';
 import { Icon } from './Icon';
 
 interface NavRailItem {
@@ -54,13 +55,20 @@ function NavRailButton({ item }: { item: NavRailItem }) {
   );
 }
 
+interface NavRailProps {
+  unreadMessages?: number;
+  /** The logged-in user's own id/name/avatar (`GET /v1/im/me`) -- drives the rail's top self-tile.
+   *  All optional so the rail still renders (as a letter-tile fallback) before that request settles. */
+  selfId?: string;
+  selfName?: string;
+  selfAvatarFileId?: string;
+}
+
 /** Persistent 64px icon rail, visible at >=640px (see App.tsx for the <640 bottom-tab fallback). */
-export function NavRail({ selfInitial = '我', unreadMessages = 0 }: { selfInitial?: string; unreadMessages?: number }) {
+export function NavRail({ unreadMessages = 0, selfId, selfName, selfAvatarFileId }: NavRailProps) {
   return (
     <nav className="flex h-full w-16 flex-none flex-col items-center border-r border-[#e6e9ee] bg-surface-rail pb-3 pt-3.5">
-      <div className="mb-[22px] grid h-[38px] w-[38px] place-items-center rounded-[10px] bg-accent text-base font-semibold text-white">
+      <Avatar id={selfId || ''} name={selfName} avatarFileId={selfAvatarFileId} className="mb-[22px] h-[38px] w-[38px] rounded-[10px] text-base" />
-        {selfInitial}
-      </div>
       <div className="flex flex-1 flex-col items-center gap-1.5">
         {TOP_ITEMS.map((item) => (
           <NavRailButton key={item.to} item={item.to === '/messages' ? { ...item, badge: unreadMessages } : item} />

web/src/features/messages/ConversationView.tsx

@@ -129,10 +129,16 @@ export function ConversationView() {
 
   useEffect(() => {
     if (!topicId) return undefined;
-    openConversation(topicId).catch(() => {});
+    // Unlike every other action in this component (see showError's own comment above), a failed
+    // subscribe here used to just vanish into an empty `.catch(() => {})` -- the user would land on
+    // a totally blank message list with no error, no retry, and (since the noteRead effect below
+    // only fires once `messages.length > 0`) a read receipt that can never be sent, leaving the chat
+    // list's unread badge permanently stuck for a conversation that in fact never loaded at all.
+    openConversation(topicId).catch((err) => showError(err, '加载会话失败，请重试'));
     return () => {
       closeConversation(topicId).catch(() => {});
     };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [topicId]);
 
   // useLayoutEffect, not useEffect -- this component never remounts on topicId change (route is