Added media notifications, fix spacebar shortcut, and more.
- Press scale animation to play button
- Lrclib search & get API fallback
- Reopen output stream at native sample rate on load to avoid unnecessary resampling
- Added hardware capability check in probe_exact_rate before opening streams
- Fixed Spacebar shortcut being swallowed when search field is focused (migrated to HardwareKeyboard)
- Added debounce guard (_playPauseBusy) to prevent backend freezes from play/pause spam
