Cut 1 completes the dormant MutationEnvelope contract without changing any runtime path. Bind target_id to the provisioned agent identity, require canonical UUID v4 authorization IDs, cap authorization lifetime at the fleet TTL, and add an unsigned MutationReceipt carrying the audit join.
Server, Agent, and helper share the same canonical bytes, key identity, receipt digest, and Ed25519 golden vectors. Current APT/DNF and Windows execution remains untouched.
