Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-19T19:38:29+00:00	DMARC	—	VALID	`613b68fdcca3…`
2026-08-19T19:38:29+00:00	SPF	—	VALID	`3db7c4ddc0f3…`