Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-21T11:47:55+00:00	DMARC	—	VALID	`dc550c5f1c48…`
2026-08-21T11:47:55+00:00	SPF	—	VALID	`0dfb80bce2a4…`