Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-21T11:16:55+00:00	DMARC	—	VALID	`5d258bde21ef…`
2026-08-21T11:16:55+00:00	SPF	—	INVALID	`b2c0cfc354cf…`