moved common out of systems

common/optional/steam.nix

@@ -0,0 +1,17 @@
+{ pkgs, ... }:
+{
+  environment.systemPackages = with pkgs; [mangohud steam-run];
+  hardware.steam-hardware.enable = true;
+
+  programs = {
+    gamemode.enable = true;
+    steam = {
+      enable = true;
+      gamescopeSession.enable = true;
+      remotePlay.openFirewall = true;
+      localNetworkGameTransfers.openFirewall = true;
+      extraCompatPackages = with pkgs; [proton-ge-bin];
+      extest.enable = true;
+    };
+  };
+}