Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-16T19:32:21+00:00	DMARC	—	VALID	`4469a0156aad…`
2026-08-16T19:32:21+00:00	SPF	—	VALID	`d2f3dda3a08b…`