* feat: add sleep timer to player bar
- Add sleep timer button in player bar right controls
- Preset options: End of song, 5/10/15/30/45 min, 1 hr, 2 hrs
- Custom timer with HH:MM:SS input fields
- Timer only counts down while music is playing
- Timer pauses playback when it expires
- End-of-song mode pauses at the next track change
- Uses theme-aware styling (--theme-colors-surface)
- Add sleepTimer/sleepTimerOff icons (LuTimer/LuTimerOff)
- Add i18n strings for sleep timer UI
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Co-authored-by: York <york@BonecharMac.local>
Co-authored-by: jeffvli <jeffvictorli@gmail.com>
York