add adaptive_scaffold

mobile-v2/lib/utils/constants/globals.dart

@@ -0,0 +1,4 @@
+import 'package:flutter/material.dart';
+
+/// Global ScaffoldMessengerKey to show snackbars
+final GlobalKey<ScaffoldMessengerState> kScafMessengerKey = GlobalKey();

mobile-v2/lib/utils/constants/size_constants.dart

@@ -0,0 +1,11 @@
+import 'package:flutter/material.dart';
+
+@immutable
+class SizeConstants {
+  const SizeConstants._();
+
+  static const s = 8.0;
+  static const m = 16.0;
+  static const l = 32.0;
+  static const xl = 64.0;
+}