📱 New layout for the landscape device

lib/widgets/sidebar/sidebar_placeholder.dart

@@ -1,15 +0,0 @@
-import 'package:flutter/material.dart';
-
-class SidebarPlaceholder extends StatelessWidget {
-  const SidebarPlaceholder({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return Material(
-      color: Theme.of(context).colorScheme.surface,
-      child: const Center(
-        child: Icon(Icons.menu_open, size: 50),
-      ),
-    );
-  }
-}