Functional Navbar + New icons

switch between pages with pageprovider

lib/pages/pageEssen.dart

@@ -0,0 +1,10 @@
+import 'package:flutter/material.dart';
+
+class PageEssen extends StatelessWidget {
+  const PageEssen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Placeholder();
+  }
+}