New user-absence endpoints added: list absent users in a time window (GET /v1/calendar/absence/users), get a single user's absence (GET /v1/calendar/absence/users/{user_id}), search absence for multiple users at once (POST /v1/calendar/absence:search), search current-moment absence for a batch of users (POST /v1/calendar/absence:search-now, returning an absent_until timestamp marking the end of any active absence), and create, read, update, and delete manual absence adjustments (.../absence/users/{user_id}/adjustments)
GET /v1/calendar/absence/users/{user_id} also returns an optional external_calendars array listing the user's connected Outlook/Google calendars and each provider's last_synced_at