Add Factory Droid to README, bump to 0.4.0, add npm publish workflow

- Document Droid as third converter target alongside OpenCode and Codex
- Bump package version 0.3.0 → 0.4.0 for new target feature
- Add CHANGELOG entry for 2.32.0 with Droid details
- Add GitHub Actions workflow to publish to npm on release

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>