- ScheduleDocument/Schedule gain optional reminderMinutes (minutes from
midnight; decode-compatible, no schema bump)
- New Workout form gets a Reminder section (toggle + time picker, hidden
for Now; footer warns when notifications are denied)
- ReminderPlanner (pure, tested) derives notification triggers: daily
repeating, per-weekday repeating for fixed days, one-shot for once
- ReminderScheduler resyncs pending requests from the cache on every
change, multiplexed onto onCacheChanged after the watch push; asks
notification permission only once a reminder actually exists