scarab: Apply scaling factor in Wayland

Sets `AVALONIA_GLOBAL_SCALE_FACTOR` to the GNOME desktop scaling factor
based on
<AvaloniaUI/Avalonia#9390 (comment)>.

pkgs/tools/games/scarab/default.nix

@@ -2,12 +2,14 @@
   lib,
   buildDotnetModule,
   fetchFromGitHub,
+  glib,
   glibc,
   zlib,
   gtk3,
   copyDesktopItems,
   icoutils,
   wrapGAppsHook3,
+  writeText,
   makeDesktopItem,
 }:
 
@@ -51,6 +53,12 @@ buildDotnetModule rec {
 
   doCheck = true;
 
+  scalingSettings = writeText "scalingSettings" ''
+    AVALONIA_GLOBAL_SCALE_FACTOR="$(${glib}/bin/gsettings get org.gnome.desktop.interface scaling-factor | cut --delimiter=' ' --fields=2)"
+    AVALONIA_GLOBAL_SCALE_FACTOR="''${AVALONIA_GLOBAL_SCALE_FACTOR:-1}"
+    export AVALONIA_GLOBAL_SCALE_FACTOR
+  '';
+
   postFixup = ''
     # Icons for the desktop file
     icotool -x $src/Scarab/Assets/omegamaggotprime.ico
@@ -60,6 +68,8 @@ buildDotnetModule rec {
       size=''${sizes[$i]}x''${sizes[$i]}
       install -D omegamaggotprime_''$((i+1))_''${size}x32.png $out/share/icons/hicolor/$size/apps/scarab.png
     done
+
+    wrapProgram "$out/bin/Scarab" --run '. ${scalingSettings}'
   '';
 
   desktopItems = [