Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-18T15:39:04+00:00	DMARC	—	VALID	`26afdbf2beb9…`
2026-08-18T15:39:03+00:00	SPF	—	VALID	`3ffac9225bb3…`