Align GitHub Pages root with the hosted emulator entrypoint

[Copilot]

The GitHub Pages root was serving stale js-dos boot code and failing with Dos is not defined, while the maintained emulator output already lived under demo/build/latest/. This change makes the root URL the canonical entrypoint and removes drift between hand-authored pages and workflow-generated Pages content.

• Canonical Pages entrypoint

  • Replaced the root index.html with a lightweight redirect/launcher to demo/build/latest/
  • Updated the README badge/link to point at the repo root, which now forwards to the latest hosted build

• Remove legacy page drift

  • Converted js-dos-test.html and jsdos-demo1.html from independent runtime experiments into redirects to the same canonical entrypoint
  • Stops multiple public pages from carrying incompatible js-dos integration code

• Pages deployment alignment

  • Changed the workflow to publish the root Pages files alongside demo/build/... from a single staging directory
  • Added the root URL to the Pages smoke-test targets so the public entrypoint stays covered by deployment validation

• Harden generated emulator page

  • Kept the deployed demo page on the workflow-owned js-dos v8 path
  • Added basic startup status/error messaging so library load failures degrade visibly instead of failing as a blank screen

• Static asset cleanup

  • Added a repository favicon so the root page no longer emits the noisy favicon.ico 404 shown in the browser console

Example of the root-page change:

<meta http-equiv="refresh" content="0; url=./demo/build/latest/">

<script>
  window.location.replace(new URL('./demo/build/latest/', window.location.href).href);
</script>