Bump version to 0.2.0 and add changelog

- Updated version constant to 0.2.0 in internal/version/version.go
- Added CHANGELOG.md documenting all features and changes
- Prepared for 0.2.0 release

Add release configuration

- Add .goreleaser.yaml for automated cross-platform builds
- Add GitHub Actions workflow for releases
- Add agent instructions for creating releases
- Configure Homebrew tap support