Find a way to deploy the static site to an appropriate host

This project is currently buidling using the CI/CD pipeline in Gitlab, but we are not pushing the generated HTML anywhere where it could be served.

We could consider enabling "gitlab pages" on git.coop and use that as the static host, or add something to the build pipeline to push the generated HTML to a server (possibly a webarchitects one).

We also need to change the DNS to point https://www.coops.tech/ to the new host.

Some instructions: https://docs.gitlab.com/ee/ci/ssh_keys/#verifying-the-ssh-host-keys