Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-19T18:03:02+00:00	DMARC	—	VALID	`b5f14c5eacdc…`
2026-08-19T18:03:02+00:00	SPF	—	VALID	`deb1fb5ec3e2…`