feat: enable custom domains for pages

applications/gitlab.nix

@@ -208,6 +208,7 @@
           # default for pages is set to 8090 but that leaves an "ugly" port in the url,
           # override it here to make it look good
           port = 80;
+          external_http = ["${cfg.host.ip}:80"];
         };
       };
     };