set wayland as default platform

flake.nix

@@ -49,6 +49,10 @@
             inherit runtimeInputs;
             text = ''
               export FONTCONFIG_FILE=${fontsConf}
+              # Force the Wayland QPA plugin: Qt defaults to xcb (X11) on Linux,
+              # so without this the bar comes up under XWayland. Honour an
+              # explicit override if the caller already set one.
+              export QT_QPA_PLATFORM="''${QT_QPA_PLATFORM:-wayland}"
               exec quickshell --path ${self} "$@"
             '';
           };