Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-18T23:24:02+00:00	DMARC	—	VALID	`207b1d68ed0c…`
2026-08-18T23:24:02+00:00	SPF	—	VALID	`b0bd10edeb20…`