Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-21T15:56:48+00:00	DMARC	—	VALID	`aa53c2bb5730…`
2026-08-21T15:56:48+00:00	SPF	—	VALID	`4d4815dd4357…`