feat(web): real chat list + P2P conversation view against live Tinode data

Phase 2 core loop: chat list and single-chat conversation now read/write real
Tinode topic data end to end, replacing the earlier hardcoded placeholders.

- lib/tinode/topics.ts: per-topic pub-sub layered on connection.ts's pattern
  (Topic.onData/onInfo/etc are single-slot callbacks, claimed once and fanned
  out). Implements the old app's subscribe lifecycle: `me` subscribed once
  per session (metadata only), each contact gets a one-shot preview
  subscription (withLaterData(1), never left), opening a conversation
  leaves-then-resubscribes with a full history page (withData, not
  withLaterData -- a preview prefetch already nudging _maxSeq would make
  withLaterData return empty).
- lib/tinode/hooks.ts: useChatList()/useTopicMessages() via
  useSyncExternalStore, snapshots cached and only invalidated on real
  topic-change notifications (not recomputed every render).
- lib/tinode/send.ts: sendText/retryMessage via createMessage+publishDraft
  (optimistic local echo), not the simpler publish() -- matches the old
  app's approach. retryMessage flushes the failed local entry and rebuilds
  before republishing, per the old app's context-menu retry handler.
- lib/messages/{time,avatar,attachments,status,preview,dispatch,drafty}:
  formatting utilities. Avatar color hash ports the old app's Java-style
  string hash but with modulus 11 (this design's palette) not the old app's
  16. @mention renders flat accent blue per the new design, not the old
  app's per-user hash color -- a deliberate simplification. File-type icons
  (PDF/Word/Excel/PPT) are new-design-only; the old app buckets all
  documents identically. Date/time formatting is written fresh against the
  design spec (today+time combined, weekday tier) since the old app never
  combines a relative-date word with a time in one string.
- ChatListColumn, MessageBubble, ConversationView: real components replacing
  the placeholder chat list and "占位" conversation view.
- tinode-sdk.d.ts: expanded with the real Topic/MetaGetBuilder/Drafty
  surface needed above, verified against the installed SDK source
  (createMessage/publishDraft/messages/msgStatus/noteRead/flushMessage/
  Drafty.format's exact treeBottomUp contract, MESSAGE_STATUS_* statics).

Verified end to end against the real backend: used the still-functional old
app (a second account, ixp355087) to create a real friendship and exchange
messages with the new app's test account, confirming the new chat list and
conversation view correctly render pre-existing real data, sending a new
message shows the right optimistic-then-delivered status transition, and
the old app receives it live in return.

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

web/src/features/messages/MessagesLayout.tsx

@@ -3,51 +3,7 @@ import { useState } from 'react';
 import { Outlet, useParams } from 'react-router-dom';
 
 import { Icon } from '@/app/Icon';
-
-const PLACEHOLDER_CHATS = [
-  { id: 'grp1', name: '项目协作群', summary: '陈明远：@我 明天上午十点开项目会，请准时参加', time: '10:24', unread: 5 },
-  { id: 'p1', name: '接语彤', summary: '我：收到，我会提前准备材料。', time: '10:12', unread: 0 },
-  { id: 'grp2', name: '产品评审群', summary: '[图片]', time: '09:47', unread: 2 },
-];
-
-function ChatListColumn() {
-  const { topicId } = useParams();
-  return (
-    <aside className="flex h-full w-full flex-none flex-col border-r border-border-panel bg-white md:w-[300px] lg:w-80">
-      <header className="flex h-15 flex-none items-center justify-between px-5">
-        <h1 className="m-0 text-xl font-semibold text-text-heading">消息</h1>
-        <Icon name="add_comment" className="text-text-heading" />
-      </header>
-      <div className="flex flex-1 flex-col overflow-y-auto">
-        {PLACEHOLDER_CHATS.map((chat) => (
-          <a
-            key={chat.id}
-            href={`/messages/${chat.id}`}
-            className={`grid min-h-[68px] grid-cols-[44px_minmax(0,1fr)_auto] items-center gap-3 border-b border-list-item px-4 py-2.5 no-underline ${
-              topicId === chat.id ? 'bg-accent-selected-bg' : 'bg-white'
-            }`}
-          >
-            <span className="grid h-11 w-11 place-items-center rounded-lg bg-avatar-1 text-base font-medium text-white">
-              {chat.name.slice(0, 1)}
-            </span>
-            <span className="flex min-w-0 flex-col gap-1">
-              <strong className="truncate text-[15px] font-medium text-[#272b31]">{chat.name}</strong>
-              <small className="truncate text-[13px] text-text-tertiary-2">{chat.summary}</small>
-            </span>
-            <span className="flex flex-none flex-col items-end justify-between gap-1.5">
-              <time className="text-xs text-text-tertiary-3">{chat.time}</time>
-              {chat.unread ? (
-                <b className="grid h-[18px] min-w-[18px] place-items-center rounded-full bg-unread px-1.5 text-[11px] font-medium text-white">
-                  {chat.unread}
-                </b>
-              ) : null}
-            </span>
-          </a>
-        ))}
-      </div>
-    </aside>
-  );
-}
+import { ChatListColumn } from '@/features/messages/ChatListColumn';
 
 function DetailColumn({ onClose }: { onClose?: () => void }) {
   return (