Remove unused file

example/lib/overlay.dart

@@ -1,95 +0,0 @@
-import 'package:flutter/material.dart';
-
-void main() {
-  runApp(App());
-}
-
-class App extends StatelessWidget {
-  const App({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return MaterialApp(
-      home: Home(),
-    );
-  }
-}
-
-class Home extends StatelessWidget {
-  const Home({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return Scaffold(
-      body: ListView(
-        children: [
-          SizedBox(
-            height: 500,
-          ),
-          OverlayDemo(),
-          SizedBox(
-            height: 2500,
-          ),
-        ],
-      ),
-    );
-  }
-}
-
-class OverlayDemo extends StatefulWidget {
-  const OverlayDemo({super.key});
-
-  @override
-  State<OverlayDemo> createState() => OverlayDemoState();
-}
-
-class OverlayDemoState extends State<OverlayDemo> {
-  final overlay = OverlayPortalController();
-  final link = LayerLink();
-
-  @override
-  Widget build(BuildContext context) {
-    return OverlayPortal(
-      controller: overlay,
-      overlayChildBuilder: (context) {
-        return CompositedTransformFollower(
-          link: link,
-          child: Stack(
-            children: [
-              Container(
-                color: Colors.yellow,
-                width: 100,
-                height: 100,
-              ),
-            ],
-          ),
-        );
-      },
-      child: MouseRegion(
-        onHover: (event) {
-          setState(() {
-            overlay.show();
-          });
-        },
-        onExit: (event) {
-          setState(() {
-            overlay.hide();
-          });
-        },
-        child: CompositedTransformTarget(
-          link: link,
-          child: GestureDetector(
-            onTap: () {
-              debugDumpLayerTree();
-            },
-            child: Container(
-              color: Colors.red,
-              width: 100,
-              height: 100,
-            ),
-          ),
-        ),
-      ),
-    );
-  }
-}