schalli
389ac9b692
feat(05-03): calendar providers (CalDAV, ICS, Exchange)
- Implement ICSProvider with fetch + node-ical parsing + RRULE expansion
- Implement CalDAVProvider with tsdav DAVClient + time-range filtering
- Implement ExchangeProvider dispatching on exchangeMode (graph vs ews)
- Graph mode uses @microsoft/microsoft-graph-client /me/calendarView
- EWS mode uses ews-javascript-api FindAppointments
- Exchange gracefully degrades: returns empty array on failure (D-08)
- No provider logs decrypted passwords (T-05-13)