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/main/runtime/app-ready-main-deps.test.ts

@@ -48,6 +48,7 @@ test('app-ready main deps builder returns mapped app-ready runtime deps', async
     startBackgroundWarmups: () => calls.push('start-warmups'),
     texthookerOnlyMode: false,
     shouldAutoInitializeOverlayRuntimeFromConfig: () => true,
+    shouldHandleInitialArgsBeforeDeferredOverlayWarmup: () => true,
     setVisibleOverlayVisible: () => calls.push('set-visible-overlay'),
     initializeOverlayRuntime: () => calls.push('init-overlay'),
     handleInitialArgs: () => calls.push('handle-initial-args'),
@@ -64,6 +65,7 @@ test('app-ready main deps builder returns mapped app-ready runtime deps', async
   assert.equal(onReady.defaultTexthookerPort, 5174);
   assert.equal(onReady.texthookerOnlyMode, false);
   assert.equal(onReady.shouldAutoInitializeOverlayRuntimeFromConfig(), true);
+  assert.equal(onReady.shouldHandleInitialArgsBeforeDeferredOverlayWarmup?.(), true);
   assert.equal(onReady.now?.(), 123);
   onReady.loadSubtitlePosition();
   onReady.resolveKeybindings();