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/HistorySearchModal.tsx

@@ -9,6 +9,7 @@ import { checkUrlSafety } from '@/lib/api/security';
 import { avatarBgClass, avatarLetter } from '@/lib/avatar';
 import { useAuthedBlobUrl, useDebouncedValue, useEscapeKey } from '@/lib/hooks';
 import { renderDrafty } from '@/lib/messages/drafty';
+import { groupSenderLabel } from '@/lib/messages/sender-name';
 import { formatEventTimestamp } from '@/lib/messages/time';
 import { requestConfirm } from '@/stores/confirmDialog';
 import { notify } from '@/stores/globalToast';
@@ -163,7 +164,7 @@ export function HistorySearchModal({ topicId, initialTab = 'text', onClose, isGr
   const senderLabel = (from: string): string => {
     const full = normalizeSender(from);
     if (myUserId && full === myUserId) return '我';
-    if (isGroup) return membersQuery.data?.find((m) => m.user_id === full)?.display_name || from;
+    if (isGroup) return groupSenderLabel(membersQuery.data?.find((m) => m.user_id === full)?.display_name);
     return peerName;
   };