feat(dist): publish package to npm registry

## Problem
Library only available via CDN, not `npm install`.

## Suggestion
1. Publish to npm: `npm publish`
2. Add to README: `npm install ajaxrequest-helper`
3. Set up CI/CD for automated publishing on release

## Benefits
- Easier integration in Node.js/bundler workflows
- Version management via package.json
- Wider discoverability