## What changed
- Define and export skill metadata, policy, dependency, interface, and configuration rule types from `codex-skills`.
- Update core, plugin, and extension consumers to use the shared models while retaining compatibility re-exports from `codex-core-skills`.
- Share product-restriction handling between host and environment skill metadata.
## Testing
- Add unit coverage for default and explicit implicit-invocation and product policies.
GitOrigin-RevId: 9093469f8fff8e2d902dc9781235f64709827a87