Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-21T14:54:42+00:00	DMARC	—	VALID	`ad06a19c7b40…`
2026-08-21T14:54:42+00:00	SPF	—	VALID	`fae2e64b8991…`