podman: don´t use default bridge network

[0xlua]

I don´t want to rely on the default podman bridge network, because every container can see any other container. I just want each container to only see other containers, when necessary.

The biggest one will be the web_ingress-network which will include all containers which need to accessed via a Web browser and therefore be reachable by caddy. This should only include containers, that were made to be exposed.

However some containers don't need to be accessed by me, only by other conatiners, e.g. PostgreSQL, Redis/Valkey, Upvote-RSS. I will create one network per inter-service communcation use-case.

Also Databases don´t need access to the Internet at all, these will be internal networks.

This example is from docker-compose and I'll have to translate it to quadlets:

    # after: database isolated, no internet
    networks:
      default:
        name: myapp_db
        internal: true
      web_ingress:
        external: true

Special cases might include Home-Assistant, Music-Assistant and Gluetun.