joy-crypt: cryptographic primitives for Joy.
Leaf crate. Owns Argon2id KDF, AES-256-GCM AEAD, Ed25519 sign/verify, seed and zone-key wrapping, Job-bound session wraps, and secret containers. No knowledge of the joy item or auth-token model; that lives in joy-core.
See ADR-039 §"Crate boundary and dependency direction" for the decision that fixes joy-crypt as the leaf crate.