KC-5: Consolidate calendar access into CalendarStore.shared so Today,
Calendar, Onboarding, and Settings share one permission state and event
cache. requestAccess() debounces and reads authoritative status; turning
on "Show Calendar Events" while unauthorized now prompts. New Settings →
Data → Calendar row shows Connected/Connect/Denied.
KC-6: Add calendar-event notifications. CalendarStore.upcomingEventNotifs
snapshots visible events (next 7 days); NotificationManager schedules at
start time plus each event alarm (all-day at 9am), capped at ~20 to stay
under iOS's 64-notification limit. Wired into reschedule().
Log KC-5 and KC-6 in ISSUES.md.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
