Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-19T07:42:40+00:00	DMARC	—	VALID	`6d5ef8e23ce0…`
2026-08-19T07:42:40+00:00	SPF	—	VALID	`4f6fb5baf7cc…`