fix(schedule): load scheduled messages from the server; offer to cancel them at logout (#322)

The tray only knew what this browser had scheduled (localStorage), but
Synapse lists every pending one via MSC4140 GET /delayed_events. Load it
when the tray mounts and on window focus (localStorage stays as a first-
paint cache), keeping only non-state m.room.message events. Logout now
says "N scheduled messages still send after you log out" and offers to
cancel them.

Fixes #322

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

src/app/utils/scheduledMessages.test.ts

@@ -6,6 +6,8 @@ import {
   scheduleMessage,
   cancelScheduledMessage,
   restartScheduledMessage,
+  parseDelayedEvents,
+  groupScheduledByRoom,
 } from './scheduledMessages';
 
 // Minimal MatrixClient stub: records every authedRequest call and returns a
@@ -119,3 +121,61 @@ test('cancel/restart url-encode the delay id', async () => {
   await cancelScheduledMessage(mx, 'a/b c');
   assert.equal(calls[0][1], '/delayed_events/a%2Fb%20c');
 });
+
+test('parseDelayedEvents: Synapse shape, messages only, sendAt from running_since + delay (#322)', () => {
+  const res = {
+    delayed_events: [
+      {
+        delay_id: 'syd_a',
+        room_id: '!r:x',
+        type: 'm.room.message',
+        content: { msgtype: 'm.text', body: 'hi' },
+        delay: 60000,
+        running_since: 1000,
+      },
+      {
+        delay_id: 'syd_call',
+        room_id: '!r:x',
+        type: 'org.matrix.msc3401.call.member',
+        state_key: '_@a:x_D',
+        content: {},
+        delay: 8000,
+        running_since: 1000,
+      },
+      { delay_id: 'syd_bad', room_id: '!r:x', type: 'm.room.message', content: {} },
+      null,
+    ],
+  };
+  assert.deepEqual(parseDelayedEvents(res), [
+    { delayId: 'syd_a', roomId: '!r:x', content: { msgtype: 'm.text', body: 'hi' }, sendAt: 61000 },
+  ]);
+});
+
+test('parseDelayedEvents: MSC `scheduled` shape and garbage', () => {
+  const item = {
+    delay_id: 'd',
+    room_id: '!r:x',
+    type: 'm.room.message',
+    content: { body: 'b' },
+    delay_ms: 5,
+    delayed_since_ts: 10,
+  };
+  assert.equal(parseDelayedEvents({ scheduled: [item] })[0].sendAt, 15);
+  assert.deepEqual(parseDelayedEvents(undefined), []);
+  assert.deepEqual(parseDelayedEvents({ delayed_events: 'nope' }), []);
+});
+
+test('groupScheduledByRoom: groups and sorts by sendAt', () => {
+  const m = (delayId: string, roomId: string, sendAt: number) => ({
+    delayId,
+    roomId,
+    content: {},
+    sendAt,
+  });
+  const g = groupScheduledByRoom([m('b', '!1', 20), m('a', '!1', 10), m('c', '!2', 5)]);
+  assert.deepEqual(
+    g.get('!1')?.map((x) => x.delayId),
+    ['a', 'b'],
+  );
+  assert.equal(g.get('!2')?.length, 1);
+});