Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T20:42:27+00:00	DMARC	—	VALID	`1d44d4162cc5…`
2026-08-20T20:42:27+00:00	SPF	—	VALID	`07cfebf48653…`