refactor(Settings): Rename fullscreen properties to overlay layer for consistency

- Updated property names from `showOverFullscreen` to `useOverlayLayer` across various components.
- Fixed Darken Modal Overlay in Standalone mode

quickshell/Common/settings/SettingsSpec.js

@@ -213,7 +213,7 @@ var SPEC = {
     dankLauncherV2UnloadOnClose: { def: false },
     dankLauncherV2IncludeFilesInAll: { def: false },
     dankLauncherV2IncludeFoldersInAll: { def: false },
-    launcherShowOverFullscreen: { def: false },
+    launcherUseOverlayLayer: { def: false },
     launcherStyle: { def: "full" },
 
     useAutoLocation: { def: false },
@@ -333,7 +333,7 @@ var SPEC = {
     showDock: { def: false },
     dockAutoHide: { def: false },
     dockSmartAutoHide: { def: false },
-    dockShowOverFullscreen: { def: false },
+    dockUseOverlayLayer: { def: false },
     dockGroupByApp: { def: false },
     dockRestoreSpecialWorkspaceOnClick: { def: false },
     dockOpenOnOverview: { def: false },
@@ -497,7 +497,7 @@ var SPEC = {
             popupGapsAuto: true,
             popupGapsManual: 4,
             maximizeDetection: true,
-            showOverFullscreen: false,
+            useOverlayLayer: false,
             scrollEnabled: true,
             scrollXBehavior: "column",
             scrollYBehavior: "workspace",