This fixes Demo https://martin.maplibre.org/ site (the new code is
already in production there). Main fixes:
* uses HTTPS again, just like the previous site
* uses nginx
* fixes all the relative paths, maplibre, minor other things
* Use `postgis/postgis` image for the DB
* Build frontend image inside the docker
* Upgrade all packages except styled-components - that one causes some
errors
* Add yarn.lock to the repo
* Add justfile for simplicity
* Bump martin docker image version in a few places
