add selinunte (desktop gaming system)

Signed-off-by: ahuston-0 <aliceghuston@gmail.com>

systems/selinunte/steam.nix

@@ -0,0 +1,20 @@
+{ pkgs, ... }:
+
+{
+  environment.systemPackages = [ pkgs.steam-run ];
+  hardware.steam-hardware.enable = true;
+  programs = {
+    gamescope = {
+      enable = true;
+      capSysNice = true;
+    };
+    steam = {
+      enable = true;
+      remotePlay.openFirewall = true;
+      localNetworkGameTransfers.openFirewall = true;
+      extraCompatPackages = with pkgs; [ proton-ge-bin ];
+      gamescopeSession.enable = true;
+      extest.enable = true;
+    };
+  };
+}