Fix production packages (ghcr) #364

Looks like the separate Dockerfile.ghcr and the docker-compose-ghcr.yml and docker-compose-ghcr-tailscale.yml have fallen our of date as the project has updated.

• Prod container can't start (gets stuck in a restart loop of exec /entrypoint.sh: no such file or directory)
• Prod compose has 2 copies of assetatlas instead of 1 assetatlas 1 migration
• Prod compose is missing tusd

• Get prod containers working again
• Figure out why we had a separate Dockerfile and Dockerfile.ghcr, and ideally reduce it to just one
• Reduce duplication in the dev docker-compose files (seems like app-mongoexpress got duplicated for example, and docker-compose.dev has stuff that's already in docker-compose. I think we intended to use the compose layering to avoid that).
• Write developer-focused docs on what needs to be updated to keep things from breaking on prod/releases (ex. update ghcr compose files)