fix: add wayland dev headers and scanner for pywayland build on NixOS

configs/quickshell/modules/common/widgets/StyledRectangularShadow.qml

@@ -0,0 +1,14 @@
+import QtQuick
+import QtQuick.Effects
+import qs.modules.common
+
+RectangularShadow {
+    required property var target
+    anchors.fill: target
+    radius: target.radius
+    blur: 0.9 * Appearance.sizes.elevationMargin
+    offset: Qt.vector2d(0.0, 1.0)
+    spread: 1
+    color: Appearance.colors.colShadow
+    cached: true
+}