Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-16T20:00:23+00:00	DMARC	—	VALID	`67f6a00cc4f2…`
2026-08-16T20:00:23+00:00	SPF	—	VALID	`113c73c2eec8…`