fix: low-tail correctness — thread notifs, call audio, OIDC expiry

Verify-then-fix batch of minor bugs; each staged diff reviewed by 2 agents
(both SHIP). Two listed items (N6 receipt-avatar refresh, H10 room-name
length reject) were already handled and left unchanged.

Threads:
- T5: a just-sent reply no longer under-notifies — `participated` also checks
  the local thread timeline for our own events, since the server-bundle
  `hasCurrentUserParticipated` lags.
- T6: a room set to "Mentions & Keywords only" no longer over-notifies Default
  thread replies — new `roomMentionsOnly` gate (behavior-identical when false;
  +4 unit tests).
- T7: thread-mode account-data writes are serialized with content carried
  forward (setAccountData is a bare PUT whose result lags the /sync echo, so
  plain serialization wouldn't stop the lost update); carry only on success.

Calls / audio:
- C-L2: a real incoming ring cancels a lingering Settings ringtone preview.
- C-L3: the ringtone AudioContext is primed on the first page gesture (via the
  always-mounted CallEmbedProvider) so the first ring after a cold load isn't
  silent.
- C-L5: useCallSpeakers depends on a stable boolean, so the tile MutationObserver
  + io.lotus.call_state subscription aren't rebuilt on every membership change.

Crypto:
- F5: the OIDC refresher forwards the freshly-refreshed token expiry
  (passed on the tokens object at runtime) as expiresInMs, so the persisted
  expiresAt no longer goes stale across reloads.

Gates: tsc 0, eslint 0, prettier clean, 860/860 tests, build ok.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/components/CallEmbedProvider.tsx

@@ -42,7 +42,7 @@ import { CallEmbed, useCallControlState } from '../plugins/call';
 import { useSelectedRoom } from '../hooks/router/useSelectedRoom';
 import { ScreenSize, useScreenSizeContext } from '../hooks/useScreenSize';
 import { useMatrixClient } from '../hooks/useMatrixClient';
-import { previewRingtone, startRingtone } from '../utils/ringtones';
+import { previewRingtone, startRingtone, unlockRingtoneAudio } from '../utils/ringtones';
 import { useCallMembersChange, useCallSession } from '../hooks/useCall';
 import { useCallJoinLeaveSounds } from '../hooks/useCallJoinLeaveSounds';
 import { useCallQuality } from '../hooks/useCallQuality';
@@ -703,6 +703,23 @@ export function CallEmbedProvider({ children }: CallEmbedProviderProps) {
 
   const { screenshare: pipScreenshare } = useCallControlState(callEmbed?.control);
 
+  // C-L3 — prime the ringtone AudioContext on the first user gesture of the
+  // session so the first incoming-call ring isn't silent (a fresh context stays
+  // suspended until a gesture, and an incoming ring has none of its own).
+  useEffect(() => {
+    const prime = () => {
+      unlockRingtoneAudio();
+      window.removeEventListener('pointerdown', prime);
+      window.removeEventListener('keydown', prime);
+    };
+    window.addEventListener('pointerdown', prime, { once: true, passive: true });
+    window.addEventListener('keydown', prime, { once: true, passive: true });
+    return () => {
+      window.removeEventListener('pointerdown', prime);
+      window.removeEventListener('keydown', prime);
+    };
+  }, []);
+
   // Sync pip mode into CallControl so it can adjust behavior accordingly
   useEffect(() => {
     if (!callEmbed) return;