android: add notifications foundation with fcm channels and deep links

docs/android-checklist.md

@@ -88,10 +88,10 @@
 - [ ] Jump to message из результатов
 
 ## 12. Уведомления
-- [ ] FCM push setup
+- [x] FCM push setup
 - [ ] Локальные уведомления для foreground
-- [ ] Notification channels (Android)
-- [ ] Deep links: open chat/message
+- [x] Notification channels (Android)
+- [x] Deep links: open chat/message
 - [ ] Mention override для muted чатов
 
 ## 13. UI/UX и темы

docs/android-smoke.md

@@ -8,6 +8,7 @@
 5. Media: send image/file/audio, image opens in viewer, audio play/pause works.
 6. Invite flow: open invite deep link (`chat.daemonlord.ru/join...`) and verify joined chat auto-opens.
 7. Session safety: expired access token refreshes transparently for API calls.
+8. Notification deep link: tap push/local notification and verify chat opens via extras.
 
 ## Baseline targets (initial)
 - Cold start to first interactive screen: <= 2.5s on mid device.