refactor(waybar): register workspace window icons

configs/nixos/modules/desktop/apps/steam.nix

@@ -23,5 +23,10 @@
     environment.systemPackages = [
       pkgs.gamescope
     ];
+
+    registry.window-icon.${config.networking.hostName}.steam = {
+      class = "[Ss]team";
+      icon = "f1b6";
+    };
   };
 }