Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-18T12:24:53+00:00	DMARC	—	VALID	`a2f7d35b9b5f…`
2026-08-18T12:24:53+00:00	SPF	—	VALID	`ec46697276ec…`