Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T10:46:53+00:00	DMARC	—	VALID	`f361fd5dd9c0…`
2026-08-20T10:46:53+00:00	SPF	—	ABSENT	`b081350f91db…`