Tags: W4G1/okf

okf v0.2.1

Changes since 0.2.0:
- okf lint subcommand with opinionated bundle health checks
- okf diff subcommand with OKF-semantics bundle diff
- okf graph: --format mermaid and --format json, dropped Graphviz --dot
- CLI exit codes aligned to sysexits.h conventions
- Parallel bundle loading with typed concept-id errors
- Borrowed frontmatter getters, Clone BundleError

okf v0.2.0