fix(server): open mountd port 20048 so NFS clients can scan and mount

showmount and the NFSv3 mount protocol need mountd reachable after querying
portmapper on 111; the server was only opening TCP 111 and 2049, causing
clients (e.g. Proxmox GUI NFS storage scan) to time out connecting to
mountd on 20048. Also adds UDP for all three ports — portmapper, nfsd, and
mountd all use both protocols.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

modules/build-types/server.nix

@@ -88,5 +88,9 @@ in
     '';
   };
 
-  networking.firewall.allowedTCPPorts = [ vars.ports.nfsRpcbind vars.ports.nfsd ];
+  # mountd (20048) is needed for showmount/NFSv3 mount protocol — without it
+  # clients can reach portmapper (111) and get the mountd port back, then
+  # time out trying to connect to it. All three ports need TCP and UDP.
+  networking.firewall.allowedTCPPorts = [ vars.ports.nfsRpcbind vars.ports.nfsd vars.ports.nfsMountd ];
+  networking.firewall.allowedUDPPorts = [ vars.ports.nfsRpcbind vars.ports.nfsd vars.ports.nfsMountd ];
 }