Fix deployment script to re-enable hacklang.org publishing

[tlil]

The current GitHub Action uses the old way of publishing the Docusaurus static website to GitHub Pages (hosted under CNAME hacklang.org), needing an SSH key (from Secrets) in order to push to site, which has now expired.

This PR fixes the publishing flow by:

• Updating the publishing job to use the latest version of actions/checkout and setup-node
• Upgrading the Node dependency from v12.x to v24
• Moving the Docusaurus source code from website/ to root
• Adding a separate deploy step, using actions/deploy-pages to publish the static build

Minor updates also covered in the PR:

• Update the I18n translation file to pick up the new phrases from
  Add Terms Of Use, Privacy Policy, and Copyright Statement #37
• Update .gitignore to remove website/ prefixes

Testing

• Merged https://github.com/tlil/hacklang.org/commit/7729fbf066310f401c18f08ef2b3d5c18db781c2 in forked repo to validate merge-specific steps (Build Docusaurus, Deploy to GitHub Pages):

• Log from the step runs (first and last job in screenshot)

[Wilfred]

LGTM, I trust you :)