feat(treewide): trim down packages

defaults/nix.nix

@@ -31,12 +31,5 @@ in
     # free up to this many bytes in an automatic invocation
     # to avoid it taking too long
     nix.settings.max-free = 5000000000; # 5GB
-
-    environment.systemPackages =
-      with pkgs;
-      lib.mkIf config.nixowos.allowAddingPackages [
-        nixd
-        nixfmt
-      ];
   };
 }