refactor(dotfiles): namespace shared flake utilities

src/dotfiles/guests.nix

@@ -275,7 +275,7 @@ let
       };
     };
 
-  files = util.collectNixFiles root;
+  files = util.flake.collectNixFiles root;
   guestFiles = lib.filterAttrs (file: type: type == "regular" && lib.hasSuffix ".nix" file) (
     builtins.readDir root
   );

src/dotfiles/modules.nix

@@ -3,5 +3,5 @@
   util,
 }:
 {
-  imports = util.collectNixFiles root;
+  imports = util.flake.collectNixFiles root;
 }

src/dotfiles/util.nix

@@ -1,6 +1,7 @@
 { flakeUtil, lib }:
-flakeUtil
-// {
+{
+  flake = flakeUtil;
+
   bridgeName = id: "br-vlan${toString id}";
 
   deriveMac =