Fix React hooks ReferenceError crashing MARBOHUB POS after login

[Copilot]

The MARBOHUB POS app was completely non-functional after login — the bundled app code references useState, useEffect, useRef, and useMemo as bare globals, but the React 18 CDN UMD build only exposes window.React and window.ReactDOM, leaving those hooks undefined.

Change

• marbohub-pos/index.html — add Object.assign(window, React) in loadApp()'s s2.onload callback, immediately after react-dom loads and before the bundled app script is injected:

s2.onload = function() {
  // React loaded → expose hooks as globals so bundled app code can call them directly
  Object.assign(window, React);
  var s3 = document.createElement("script");
  s3.id = "app-js";
  s3.textContent = document.getElementById("app-src").textContent;
  document.body.appendChild(s3);
};

This promotes all React exports onto window, resolving the ReferenceError: useState is not defined crash and allowing the dashboard to render.

• Fixes THAM #11