Deterministic validator for Open Knowledge Format (OKF) bundles. Checks spec conformance (root index.md carries only okf_version, subdirectory index.md files carry no frontmatter, every concept has a non-empty type) plus enrichment coverage (placeholder descriptions, broken cross-links, orphans), and gates CI via its exit code. Use to validate an OKF bundle before publishing or ingestion, or to fail a build when a bundle regresses. Complements skills-ref validate, which only checks SKILL.md frontmatter.
