Add joafri image metadata in compose and multi-arch build/push script

Apps/steam-headless/docker-compose.yaml

@@ -1,5 +1,9 @@
 name: steam-headless
 
+x-image:
+  namespace: ${IMAGE_NAMESPACE:-joafri}
+  tag: ${IMAGE_TAG:-main}
+
 services:
   steam:
     image: lscr.io/linuxserver/steam:version-f4f48542@sha256:d7b9fbf302e05ae79248d1171fe9751b354f8397eafa1e13a3df0aa6a75de0b4