Apps, refactor, clean up, remove librewolf

Refactors to use app.nix for easier extension.

Removes librewolf from host, as it makes more sense on the user every
time.

nixosModules/apps/shells/app.nix

@@ -1,4 +1,4 @@
-{ config, pkgs, lib, ... }:
+{ ... }:
 
 {
   imports = [