Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-17T16:56:32+00:00	DMARC	—	VALID	`30d8ed25bef7…`
2026-08-17T16:56:32+00:00	SPF	—	VALID	`1ff73dcee55c…`