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/steam/app.nix

@@ -0,0 +1,17 @@
+{ config, lib, ... }:
+
+{
+  options.steam = {
+    enable = lib.mkEnableOption "Enables steam";
+    gamemode = lib.mkEnableOption "Enables gamemode";
+  };
+
+  config = lib.mkIf config.steam.enable {
+    programs.steam = {
+      enable = true;
+      remotePlay.openFirewall = true;
+      dedicatedServer.openFirewall = true;
+    };
+    programs.gamemode.enable = lib.mkIf config.steam.gamemode true;
+  };
+}