Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T08:41:59+00:00	DMARC	—	VALID	`3c4560f84e8b…`
2026-08-20T08:41:59+00:00	SPF	—	VALID	`3ffac9225bb3…`