- Add SkillOrigin::Bundled variant to support bundled skills registry
- Implement bundled_skill_root() function for discovering bundled skills
- Update skill discovery to include bundled skills from standard install paths
- Create example bundled skills (example-skill, chain-example)
- Add comprehensive tests for bundled skills discovery and metadata
- Bundled skills follow same directory structure as plugins
- Skills can now chain/invoke other skills using standard dispatch mechanisms
- Maintains backward compatibility with existing SkillsDir and LegacyCommandsDir