feat: P1 features — voice speed, private receipts, room filter, favorites, invite link, poll creation

P1-5: Voice message playback speed toggle (0.75×/1×/1.5×/2×) in AudioContent.tsx
P1-10: Private read receipts toggle in Privacy settings; wired to notifications.ts
P1-3: Room filter input on Home tab and DMs tab (client-side, clears on tab switch)
P1-8: Favorite rooms via m.favourite tag — Favorites section in Home sidebar, star/unstar in right-click menu
P1-9: Room invite link + QR code in room settings (Share Room tile, api.qrserver.com QR)
P1-6: Poll creation modal in composer (PollCreator.tsx, sends m.poll.start)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/utils/notifications.ts

@@ -1,6 +1,8 @@
 import { MatrixClient, ReceiptType } from 'matrix-js-sdk';
+import { getSettings } from '../state/settings';
 
 export async function markAsRead(mx: MatrixClient, roomId: string, privateReceipt: boolean) {
+  const { privateReadReceipts } = getSettings();
   const room = mx.getRoom(roomId);
   if (!room) return;
 
@@ -21,6 +23,6 @@ export async function markAsRead(mx: MatrixClient, roomId: string, privateReceip
 
   await mx.sendReadReceipt(
     latestEvent,
-    privateReceipt ? ReceiptType.ReadPrivate : ReceiptType.Read,
+    privateReceipt || privateReadReceipts ? ReceiptType.ReadPrivate : ReceiptType.Read,
   );
 }