implemented basic layout & functionality for add group button & group tiles

lib/presentation/widgets/top_centered_message.dart

@@ -1,14 +1,21 @@
 import 'package:flutter/material.dart';
 
-Widget TopCenteredMessage(String message) {
-  return Container(
-    padding: EdgeInsets.only(top: 100),
-    margin: EdgeInsets.only(left: 10, right: 10),
-    alignment: Alignment.topCenter,
-    child: Text(
-      "$message",
-      style: TextStyle(fontSize: 20),
-      textAlign: TextAlign.center,
-    ),
-  );
+class TopCenteredMessage extends StatelessWidget {
+  const TopCenteredMessage({super.key, required this.message});
+
+  final String message;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      padding: const EdgeInsets.only(top: 100),
+      margin: const EdgeInsets.symmetric(horizontal: 10),
+      alignment: Alignment.topCenter,
+      child: Text(
+        message,
+        style: const TextStyle(fontSize: 20),
+        textAlign: TextAlign.center,
+      ),
+    );
+  }
 }