Build and push server image / build-and-push (push) Failing after 10s
Docker defaults to HTTPS for any non-docker.io registry, and 10.0.0.246:3000 (a bare LAN IP:port) isn't serving valid HTTPS -- the push kept going out over HTTPS and failing. Adds a buildkitd config telling BuildKit specifically to use HTTP for that host. This only fixes the actual build+push step (BuildKit). The "Log in" step runs a plain `docker login` through the classic Docker CLI/daemon instead, which doesn't read this config -- that one still needs 10.0.0.246:3000 added to "insecure-registries" in the actual Docker daemon's /etc/docker/daemon.json on whatever host runs the Gitea Actions runner, followed by a daemon restart. That's runner-host infrastructure outside this repo.