Improve stackforge package discovery metadata

[rogerchappel]

What changed

• Added accurate package keywords for npm/GitHub discovery.

Why it matters

Developers browsing the package can understand the project category without reading the full README first, and package indexes get more accurate metadata.

Verification

• node -e "const p=require('./package.json'); if (!Array.isArray(p.keywords) || p.keywords.length < 3) process.exit(1)": pass
• npm pack --dry-run: pass

Remaining limitations

No runtime behavior changes were made.