Implement message_list

flutter/lib/components/bottom_fab/center_about.dart

@@ -0,0 +1,20 @@
+import 'package:flutter/material.dart';
+
+class CenterAbout extends StatelessWidget {
+  final Offset position;
+  final Widget child;
+
+  const CenterAbout({super.key, required this.position, required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    return Positioned(
+      top: position.dy,
+      left: position.dx,
+      child: FractionalTranslation(
+        translation: const Offset(-0.5, -0.5),
+        child: child,
+      ),
+    );
+  }
+}