add zen-browser as standard application module

flake.nix

@@ -25,11 +25,11 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
-    /* zen-browser = {
+    zen-browser = {
       url = "github:0xc000022070/zen-browser-flake";
       inputs.nixpkgs.follows = "nixpkgs";
       inputs.home-manager.follows = "home-manager";
-    }; */
+    };
 
     firefox-addons = {
       url = "gitlab:rycee/nur-expressions?dir=pkgs/firefox-addons";