integrate htpc and associated configuration

modules/gui/apps/steam.nix

@@ -0,0 +1,17 @@
+{ pkgs, ... }:
+
+{
+  programs.steam = {
+    enable = true;
+    gamescopeSession.enable = true;
+    extraCompatPackages = with pkgs; [
+      proton-ge-bin
+    ];
+    localNetworkGameTransfers.openFirewall = true;
+  };
+  programs.gamemode.enable = true;
+  programs.gamescope = {
+    enable = true;
+    capSysNice = true;
+  };
+}

modules/gui/services/fcast.nix

@@ -0,0 +1,6 @@
+{
+  programs.fcast-receiver = {
+    enable = true;
+    openFirewall = true;
+  };
+}

modules/gui/services/xdg.nix

@@ -1,3 +1,8 @@
+{ pkgs, ... }:
+
 {
-  xdg.portal.enable = true;
+  xdg.portal = {
+    enable = true;
+    extraPortals = [ pkgs.xdg-desktop-portal-gtk ];
+  };
 }