Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-17T15:53:59+00:00	DMARC	—	VALID	`3e6755525ce7…`
2026-08-17T15:53:59+00:00	SPF	—	VALID	`a88aa7363fcb…`