added steam module

homeManagerModules/steam.nix

@@ -0,0 +1,10 @@
+{ config, pkgs, lib, ... }:
+{
+  programs.steam = lib.mkIf config.steam {
+    enable = true;
+    gamescopeSession.enable = true;
+    remotePlay.openFirewall = true; # Open ports in the firewall for Steam Remote Play
+    dedicatedServer.openFirewall = true; # Open ports in the firewall for Source Dedicated Server
+    localNetworkGameTransfers.openFirewall = true; # Open ports in the firewall for Steam Local Network Game Transfers
+  };
+}