Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-18T14:18:42+00:00	DMARC	—	VALID	`29eb62cf8d5e…`
2026-08-18T14:18:42+00:00	SPF	—	ABSENT	`b081350f91db…`