refactor(dotfiles): split registry responsibilities

configs/nixos/registry/route.nix

@@ -1,14 +1,14 @@
-{ lib, ... }:
+{ lib, util, ... }:
 {
   checks = [
     {
-      assertion = lib.registry.predicates.uniqueValue (entry: entry.value.domain);
+      assertion = util.registry.predicates.uniqueValue (entry: entry.value.domain);
       message = "Route domains must be unique.";
     }
     {
       assertion =
         entries:
-        lib.registry.predicates.uniqueValue (entry: entry.value) (
+        util.registry.predicates.uniqueValue (entry: entry.value) (
           lib.concatMap (entry: map (port: entry // { value = port; }) entry.value.udp.ports) entries
         );
       message = "Route UDP ports must be unique.";