v0.7.0

Added

• skillgate zk-keygen, zk-policy-id, zk-prove, and zk-verify — issue and verify
  challenge-bound BBS selective-disclosure proofs that reveal only PASS and an approved
  policy hash while hiding the private repository snapshot, gate details, evidence, reasons,
  and count. The commands fail closed on a failing gate, wrong signer, wrong policy, replayed
  challenge, or altered proof. This is explicitly an experimental signer attestation, not a
  zkVM proof of the gate evaluator.