Fix browser global export for GitHub Pages demo

[Copilot]

The GitHub Pages demo was loading index.html without a usable window.vaRRI, which blocked rendering and left the color pickers initialized to the browser fallback instead of the library defaults. This change makes the browser export path resilient when a CommonJS-style module.exports object is also present.

• Browser export path

  • Publish vaRRI to the browser global unconditionally in browser-like environments.
  • Preserve the existing CommonJS export for Node/Jest consumers.

• Demo bootstrap impact

  • Restores index.html access to vaRRI.render() and vaRRI.getColors().
  • Ensures the visualization and color picker defaults come from the library again.

• Regression coverage

  • Add a focused test for the mixed environment that exposed the bug: window present alongside module.exports.

global.vaRRI = vaRRI;
if (typeof module !== 'undefined' && module.exports) {
    module.exports = vaRRI;
}