candidate.list createdAfter Now Filters on Added-At

The candidate.list createdAfter filter now compares against the candidate's added-at timestamp (COALESCE(added_at, created_at)), matching the field shown in the Ashby UI as "Added At" and the existing sort order on this endpoint.
For most candidates these timestamps are identical and behaviour is unchanged. Where they differ (typically by minutes), results will reflect the added-at value.