Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-16T19:59:13+00:00	DMARC	—	VALID	`eaa3db7f98ad…`
2026-08-16T19:59:13+00:00	SPF	—	VALID	`084eba6212f9…`