feat(notifications): add notification history panel and overlay UX fixes

- New toggleNotificationHistory (Ctrl+N) session-scoped history panel; slides in from same edge as notification stack
- Overlay error/recovery toast follows notifications.overlayPosition; stack and history side seeded at startup
- Cold managed background startup initializes tray and visible overlay shell before tokenization warmups finish
- Add Update button to overlay update-available notifications
- Fix Ctrl+S sentence-card flow: only Anki progress notification, no duplicate status toast
- Fix overlay notification close/actions clickability above subtitle bars on Linux
- Increase pause-until-ready default timeout from 15s to 30s

src/renderer/overlay-notification-history.test.ts

@@ -0,0 +1,100 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import type { OverlayNotificationEntry } from './overlay-notifications';
+import {
+  createOverlayNotificationHistoryStore,
+  resolveHistorySideFromStack,
+} from './overlay-notification-history';
+
+function entry(
+  overrides: Partial<OverlayNotificationEntry> & { id: string },
+): OverlayNotificationEntry {
+  return {
+    title: overrides.title ?? overrides.id,
+    persistent: false,
+    createdAt: 0,
+    ...overrides,
+  };
+}
+
+test('history store lists newest entries first', () => {
+  const store = createOverlayNotificationHistoryStore();
+  store.record(entry({ id: 'a', title: 'A' }));
+  store.record(entry({ id: 'b', title: 'B' }));
+  store.record(entry({ id: 'c', title: 'C' }));
+
+  assert.deepEqual(
+    store.list().map((item) => item.id),
+    ['c', 'b', 'a'],
+  );
+  assert.equal(store.size(), 3);
+});
+
+test('history store updates an entry in place without reordering or duplicating', () => {
+  let clock = 100;
+  const store = createOverlayNotificationHistoryStore({ now: () => clock });
+  store.record(entry({ id: 'job', title: 'Working', body: 'Step 1', variant: 'progress' }));
+  store.record(entry({ id: 'other', title: 'Other' }));
+  clock = 200;
+  store.record(entry({ id: 'job', title: 'Done', body: 'Step 2', variant: 'success' }));
+
+  const list = store.list();
+  assert.equal(store.size(), 2);
+  // Newest-first ordering is by first-seen; the in-place update keeps 'other' on top.
+  assert.deepEqual(
+    list.map((item) => item.id),
+    ['other', 'job'],
+  );
+  const job = list.find((item) => item.id === 'job');
+  assert.equal(job?.title, 'Done');
+  assert.equal(job?.body, 'Step 2');
+  assert.equal(job?.variant, 'success');
+  assert.equal(job?.createdAt, 100);
+  assert.equal(job?.updatedAt, 200);
+});
+
+test('history store removes and clears entries', () => {
+  const store = createOverlayNotificationHistoryStore();
+  store.record(entry({ id: 'a' }));
+  store.record(entry({ id: 'b' }));
+
+  store.remove('a');
+  assert.deepEqual(
+    store.list().map((item) => item.id),
+    ['b'],
+  );
+
+  store.clear();
+  assert.equal(store.size(), 0);
+  assert.deepEqual(store.list(), []);
+});
+
+test('history store caps to max and drops the oldest entries', () => {
+  const store = createOverlayNotificationHistoryStore({ max: 2 });
+  store.record(entry({ id: 'a' }));
+  store.record(entry({ id: 'b' }));
+  store.record(entry({ id: 'c' }));
+
+  assert.equal(store.size(), 2);
+  assert.deepEqual(
+    store.list().map((item) => item.id),
+    ['c', 'b'],
+  );
+});
+
+test('history store defaults missing variant to info', () => {
+  const store = createOverlayNotificationHistoryStore();
+  store.record(entry({ id: 'a' }));
+  assert.equal(store.list()[0]?.variant, 'info');
+});
+
+test('panel side mirrors the notification stack position', () => {
+  const stackWith = (positionClass: string) =>
+    ({ classList: { contains: (token: string) => token === positionClass } }) as unknown as Element;
+
+  assert.equal(resolveHistorySideFromStack(stackWith('position-top-left')), 'left');
+  assert.equal(resolveHistorySideFromStack(stackWith('position-top-right')), 'right');
+  // Center notifications open the panel from the right.
+  assert.equal(resolveHistorySideFromStack(stackWith('position-top')), 'right');
+});