Recurring gift mapping requires the NXT System ID

For GiveCampus integrations and API.

In Missing Recurring Gift ID, enter the existing NXT recurring gift's System ID, not an unrelated gift lookup code. Validation fetches the gift by that value, requires RecurringGift type, and rejects an ID already associated with another GC recurring subscription. A row moving to Pending indicates the workflow progressed; it does not confirm completed export.