Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-17T18:00:27+00:00	DMARC	—	VALID	`b1c8a13cd66e…`
2026-08-17T18:00:27+00:00	SPF	—	ABSENT	`b081350f91db…`