Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-16T22:59:29+00:00	DMARC	—	VALID	`774b7d90f59f…`
2026-08-16T22:59:29+00:00	SPF	—	ABSENT	`b081350f91db…`