Get the clinic's appointment reason vocabularies (ITE-899). Readable by any authenticated user: everyone who can reschedule picks from this list.

Reasons staff may pick when rescheduling. On read, the clinic's list or the defaults if it never set one. On write, the full list; empty means "offer no reasons"; omitted (null) leaves the clinic's list unchanged.

Reasons staff may pick when cancelling (ITE-905). Same read/write rules as List<string>? AppointmentReasonSettingsDto.RescheduleReasons — in particular, a PATCH that omits it (an older client that only knows about reschedule reasons) leaves the list unchanged.