refactor: abstract docker network creation via custom options

modules/apps/calibre/default.nix

@@ -57,19 +57,10 @@ in {
       };
 
       # Make sure the Docker network exists.
-      systemd.services."docker-${networkName}-create-network" = {
+      homelab.dockerNetworks."${networkName}" = {
         requiredBy = [
           "docker-calibre.service"
         ];
-        serviceConfig = {
-          Type = "oneshot";
-          RemainAfterExit = true;
-        };
-        script = ''
-          if ! ${pkgs.docker}/bin/docker network ls | grep -q ${networkName}; then
-            ${pkgs.docker}/bin/docker network create ${networkName}
-          fi
-        '';
       };
     })