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/features/settings/general/General.tsx

@@ -861,6 +861,10 @@ function Editor() {
 function Privacy() {
   const [hideActivity, setHideActivity] = useSetting(settingsAtom, 'hideActivity');
   const [hidePresence, setHidePresence] = useSetting(settingsAtom, 'hidePresence');
+  const [privateReadReceipts, setPrivateReadReceipts] = useSetting(
+    settingsAtom,
+    'privateReadReceipts',
+  );
 
   return (
     <Box direction="Column" gap="100">
@@ -872,6 +876,19 @@ function Privacy() {
           after={<Switch variant="Primary" value={hideActivity} onChange={setHideActivity} />}
         />
       </SequenceCard>
+      <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
+        <SettingTile
+          title="Private Read Receipts"
+          description="Send read receipts only to you and the server — other users won't see when you've read messages."
+          after={
+            <Switch
+              variant="Primary"
+              value={privateReadReceipts}
+              onChange={setPrivateReadReceipts}
+            />
+          }
+        />
+      </SequenceCard>
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile
           title="Hide Online Status"