fix(notifications): timed mutes are lifted by any Lotus device, not just the one that set them (#333)

A timed mute writes a server-side push rule (muted everywhere), but the
unmute timer lived in one browser's localStorage: close that laptop and
the room stayed muted on the phone until it was reopened, and forever
after a logout there. Timers now live in account data
(io.lotus.mute_timers: { timers: { [roomId]: unmuteAt } }). Every
client schedules from it, reschedules when it changes, and the first one
online after expiry unmutes. An indefinite mute clears a pending timer.
Local timers from before are migrated once.

Fixes #333

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/room-nav/muteTimers.test.ts

@@ -1,7 +1,7 @@
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
 import { RoomNotificationMode } from '../../hooks/useRoomsNotificationPreferences';
-import { shouldResetMuteOnUnmute } from './muteTimers';
+import { muteTimersContent, parseMuteTimers, shouldResetMuteOnUnmute } from './muteTimers';
 
 test('resets to Unset when the room is still Mute at expiry', () => {
   assert.equal(shouldResetMuteOnUnmute(RoomNotificationMode.Mute), true);
@@ -18,3 +18,16 @@ test('does not reset when the user switched to Special messages during the mute
 test('does not reset when the mode is already Unset', () => {
   assert.equal(shouldResetMuteOnUnmute(RoomNotificationMode.Unset), false);
 });
+
+test('parseMuteTimers / muteTimersContent round-trip and tolerate garbage (#333)', () => {
+  const entries = [
+    { roomId: '!a:x', unmuteAt: 1000 },
+    { roomId: '!b:x', unmuteAt: 2000 },
+  ];
+  assert.deepEqual(parseMuteTimers(muteTimersContent(entries)), entries);
+  assert.deepEqual(parseMuteTimers({ timers: { '!a:x': 'soon', '!b:x': 5 } }), [
+    { roomId: '!b:x', unmuteAt: 5 },
+  ]);
+  assert.deepEqual(parseMuteTimers(undefined), []);
+  assert.deepEqual(parseMuteTimers({ timers: null }), []);
+});