PostgreSQL implementation of Attesto.RefreshStore.

Rotation is one family-serialized transaction. The transaction locks the family with a transaction-scoped advisory lock, locks the parent row, marks the parent consumed with its authenticated retry state, and inserts the successor before it commits. A blocked caller therefore sees either the complete committed winner or a complete reuse record; it can never observe a consumed parent before its successor exists.

Positive retry state is authenticated-encrypted before the transaction. The encryption key must be stable across every node that can serve the family. Strict rotation stores only %{retry_until: now, recoverable: false} and needs no encryption secret. Expired retry state is redacted by the sweeper, while a consumed parent is retained until that deadline or its own expiry, whichever comes first. Family revocation is also recorded in the separate RefreshFamilyRevocation table, whose tombstones are never swept.