- Add reminder editor (presets + custom number+unit) wired through save
- Per-calendar reminder mute: filter-sheet toggle + greyed-out editor hint;
reminders are kept, never deleted
- New AlarmManager-based NotificationScheduler + channel + POST_NOTIFICATIONS;
skips muted calendars
- New synced setting default_event_duration_minutes for new events
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
