fix(messages): never render raw uid as group sender name (#32)

Senders missing from the member list (left/removed) fell back to msg.from verbatim, and nameless members arrive from the REST API with the uid itself as display_name. Resolve both through a shared groupSenderLabel helper that substitutes a fixed placeholder for uid-shaped names (message bubbles, quoted replies, history search).

web/src/features/messages/ConversationView.tsx

@@ -27,6 +27,7 @@ import { availableActions, recallRemainingSeconds, type MessageAction } from '@/
 import { isRecalled } from '@/lib/messages/dispatch';
 import { renderDrafty } from '@/lib/messages/drafty';
 import { buildMentionedContent, detectMentionTrigger, type PendingMention } from '@/lib/messages/mentions';
+import { groupSenderLabel } from '@/lib/messages/sender-name';
 import { sendFile, sendImage, sendVoice } from '@/lib/tinode/attachments';
 import { isTopicGone } from '@/lib/tinode/errors';
 import { useChatList, useTinode, useTopicMessages } from '@/lib/tinode/hooks';
@@ -568,7 +569,7 @@ export function ConversationView() {
   // second, divergent resolution path.
   const quotedSenderLabel = (fromUserId: string | undefined) => {
     if (myUserId && fromUserId === myUserId) return '我';
-    if (isGroup && fromUserId) return memberByUserId.get(fromUserId)?.display_name || fromUserId;
+    if (isGroup && fromUserId) return groupSenderLabel(memberByUserId.get(fromUserId)?.display_name);
     return peerName;
   };