Show application window when clicking on notification

## Summary
When I enable desktop notifications, I'd expect that clicking on the notification opens the Pomodorolm application window so that I can pause or skip the next session/break, if needed. But right now clicking on the notification only closes the notification.

## 🧑‍💻 Desktop:
- OS: Bazzite v43.20260101 (Fedora Universal Blue Linux)
- GNOME Desktop v49.1
- Pomodorolm v0.7.0 Flatpak