Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-21T08:06:46+00:00	DMARC	—	VALID	`a03627b25d53…`
2026-08-21T08:06:46+00:00	SPF	—	VALID	`ff1632a2dcd5…`