nx_access_audit.nx

nx_access_audit.nx -- TAMPER-EVIDENT append-only audit log for the access wall (L6; NIST AU family). Every PDP decision (subject, peer-IP, resource, action, verdict-code) is recorded as an entry CHAINED by hash: h[0] = sha256(genesis || entry0); h[i] = sha256(h[i-1] || entry_i) Any alteration, deletion, insertion, or REORDER of entries breaks the chain, so aa_verify (replay) returns 0. This is the forensic record of who was allowed/denied where + why. Reuses the KAT-verified nx_sha256 (no rolled crypto); pairs with the framed-append durability floor (the bytes on disk) -- this adds the integrity proof on top. license_tier: ORIGINAL