Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-16T23:53:59+00:00	DMARC	—	VALID	`4c577bf9d10d…`
2026-08-16T23:53:59+00:00	SPF	—	VALID	`e2b1c4567598…`