Persist a pending MFA transaction.
Renamed from save in v0.5.1 (AS-11) to align with map-like store
semantics (UserSessionStore, KeyStore). The old save name is
no longer accepted; the v0.5.1 hotfix policy explicitly permits this
rename for an interface that was new in v0.5.0.
Retrieve a pending transaction by id. Implementations MAY filter expired transactions (return null when
expiresAt <= now); core also rejects expired transactions after retrieval as defense in depth. Either behavior is acceptable.Renamed from
loadin v0.5.1 (AS-11) — see MfaTransactionStore.set.