use LazyLoader for backdrop windows, no QtQuick import needed

shell.qml

@@ -1,6 +1,5 @@
 //@ pragma Env QS_NO_RELOAD_POPUP=1
 
-import QtQuick
 import "modules"
 import Quickshell
 
@@ -24,16 +23,16 @@ ShellRoot {
                 screen: scope.modelData
             }
 
-            Loader {
+            LazyLoader {
                 active: Modules.backgroundOverlay.enable
-                sourceComponent: BackgroundOverlay {
+                BackgroundOverlay {
                     screen: scope.modelData
                 }
             }
 
-            Loader {
+            LazyLoader {
                 active: Modules.overviewBackdrop.enable
-                sourceComponent: OverviewBackdrop {
+                OverviewBackdrop {
                     screen: scope.modelData
                 }
             }