ci: automate GitHub Releases

[egdev6]

Closes #1

Type

• Bug fix
• New feature
• Documentation only
• Code refactoring
• Maintenance/tooling
• Breaking change

Summary

• Add an idempotent GitHub Actions workflow for annotated version tags and generated-notes releases.
• Run the existing test suite on pull requests and before release creation.
• Document installation and release behavior, including explicit npm publication non-goals.

Changes

File	Change
.github/workflows/release.yml	Test pull requests and create missing tags/releases after pushes to main.
README.md	Document installation, release behavior, idempotency, and non-goals.

Test plan

• npm test — 26 passed, 0 failed.
• git diff --check passed.
• Workflow parsed successfully with PyYAML 6.0.3.
• All four embedded shell blocks passed bash -n.
• Shellcheck applicability reviewed; no standalone shell scripts changed.

Contributor checklist

• Linked approved issue ci: automate idempotent GitHub Releases #1.
• Added exactly one type:* label.
• Verified all modified executable shell content.
• Confirmed no skill artifacts were changed.
• Updated documentation for the new behavior.
• Used a Conventional Commit message.
• Added no Co-Authored-By trailers.