- MainActivity: request POST_NOTIFICATIONS on TIRAMISU+, register FCM token when user signs in
- AppMessagingService: foreground chat messages show draggable bubble instead of OS notification
- MessageBubbleController/Overlay: new in-app chat-head that drifts over all screens, tap to open
- PartnerNotificationManager: GAME_RESULTS_READY type with proper copy, partner_finished_game maps to it
- onGameSessionUpdate: notify BOTH partners on completion (not just the non-starter), fix starter name in notification