//! `cph-schema` — kind JSON Schemas (ADR-0006) + structural validation.
//!
//! Owned by **WU-3**. The schema layer reads each kind's declarative JSON
//! Schema (built-in scalars plus the `content` extension type) and validates
//! element instance data against it, including which `content` `.typ` files
//! must exist.

// WU-3: implement the 4 stdlib kind schemas (segment / example / lemma / sop)
// and the validation entry point. Empty for now so the workspace compiles.