Improve atomcommit contributor lint workflow

[rogerchappel]

What changed

• Added a standard npm run lint alias that delegates to the existing static check.

Why it matters

• Contributors and automation can use the common lint command without knowing this repo-specific check name.

Verification

• npm install --package-lock=false
• npm run lint

Remaining limitations

• This does not broaden lint coverage; it exposes the existing check through a conventional script.