zk-authorship: CLI for anonymous file authorship attestations

[selfradiance]

Built a small stateless CLI on Semaphore v4 that binds a file's SHA-256 hash to an anonymous group membership proof.
Use case: prove "a member of this group made this exact file" without revealing which member. Bring-your-own-group: the tool takes a plain JSON list of identity commitments and never runs or hosts a registry. Verification is fully offline; scope defaults to group root + file hash, so the nullifier exposes duplicate attestations by the same anonymous member without identifying them.
Three commands: identity (create/show a local identity), attest (generate proof for a file against a group), verify (hash check, root check, proof check, distinct errors for each).
Repo includes a SKILL.md so AI agents can install and invoke it autonomously: https://github.com/selfradiance/zk-authorship
npm: npx zk-authorship
Feedback welcome, especially on scope construction and whether the attestation format is missing anything verifiers would want.