SleepTimerMenu is a new shared player primitive (moon icon, popover
with 5/15/30/45/60-minute presets plus End-of-chapter). Hook state in
useAudiobookPlayback drives both the countdown label and the auto-pause:
duration timers track wall-clock so they survive tab inactivity, and
end-of-chapter watches currentChapter.end_seconds. Both modes pause the
audio element and reset the setting when they fire. Wired into the
right rail of MiniBar and into the utility row of NowListening.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
