Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T12:52:43+00:00	DMARC	—	VALID	`5bcaa704cb2f…`
2026-08-20T12:52:43+00:00	SPF	—	VALID	`64b0051f2f88…`