Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-17T18:32:00+00:00	DMARC	—	VALID	`a2e4402b338b…`
2026-08-17T18:32:00+00:00	SPF	—	VALID	`347ab210eec0…`