feat: add new host and start modularizing system configuration

modules/nixos/gaming.nix

@@ -0,0 +1,17 @@
+{ config, lib, pkgs, ... }:
+{
+  environment.systemPackages = with pkgs; [
+    mangohud
+    protonup-qt
+    lutris
+    bottles
+    heroic
+  ];
+  programs.steam = {
+    enable = true;
+    remotePlay.openFirewall = true;
+    localNetworkGameTransfers.openFirewall = true;
+    protontricks.enable = true;
+    gamescopeSession.enable = true;
+  };
+}