Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T20:10:20+00:00	DMARC	—	VALID	`d5ccd0d2b0b3…`
2026-08-20T20:10:20+00:00	SPF	—	VALID	`0644ed72fee6…`