Refactor user management functions to use inputs

Removed the `lib.nix` file and refactored various modules to utilize `inputs.self.lib` for user package and attribute management. This change enhances consistency and maintainability across the configuration files.

modules/apps/art.nix

@@ -1,5 +1,6 @@
 {
   config,
+  inputs,
   lib,
   pkgs,
   ...
@@ -40,7 +41,6 @@ in
     dev.gameDev.enable = lib.mkEnableOption "game development tools and engines";
   };
   config.users.users = let
-    userLib = import ../lib.nix { inherit lib; };
     packages = artPackages ++ gameDevPackages;
-  in userLib.mkUserPackages config.my.toggleUsers.apps packages;
+  in inputs.self.lib.mkUserPackages lib config.my.toggleUsers.apps packages;
 }