Reorganize modules

modules/gaming.nix

@@ -0,0 +1,19 @@
+{ config, pkgs, ... }:
+
+{
+  programs.steam = {
+    enable = true;
+    remotePlay.openFirewall = true;
+    localNetworkGameTransfers.openFirewall = true;
+    package = pkgs.steam.override {
+      extraEnv = {
+        MANGOHUD = "1";
+        WINE_VK_VULKAN_ONLY = "1";
+      };
+    };
+  };
+
+  environment.systemPackages = [
+    pkgs.mangohud
+  ];
+}