simple-site: 404s, staging noindex and deploy tidy-up

simple-site: unknown pages now return a proper 404, and the Umbraco.AI connector is back
simple-site: staging copy on clean.jumoo.co.uk kept out of search engines
simple-site: deploy branch keeps a linear history
simple-site: new script to check a deployed copy of the site
simple-site: site starts in light mode whatever the system prefers