Audit-log anchors

Every audit event in Dokkettis linked to the previous one by a SHA-256 hash chain. Periodically, a Merkle root over the entire chain is computed and submitted to an independent RFC 3161 timestamp authority (FreeTSA). The returned token attests that the root existed at that moment, in a form Dokkett cannot backdate or alter. Any later change to a recorded event changes the recomputed root and no longer matches a published anchor.