Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-17T00:34:30+00:00	DMARC	—	VALID	`48575e52f9b2…`
2026-08-17T00:34:30+00:00	SPF	—	VALID	`d90b40540496…`