Improve bargekit package readiness

[rogerchappel]

What changed

• Added package repository/support metadata and npm package support files where missing.
• Documented local verification commands in the README when they were not already listed.

Why it matters

Users inspecting the package or npm tarball can find the source, issue tracker, support docs, and the same checks maintainers run before release.

Verification

• npm install: pass
• npm test: pass
• npm run package:smoke: pass

Follow-up

• No release was published or tagged.