Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T21:43:37+00:00	DMARC	—	VALID	`53413d63a2b5…`
2026-08-20T21:43:37+00:00	SPF	—	ABSENT	`b081350f91db…`