feat: New onboarding design

lib/widgets/layouts/login_scaffold.dart

@@ -0,0 +1,45 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+
+class LoginScaffold extends StatelessWidget {
+  final Widget body;
+  final AppBar? appBar;
+
+  const LoginScaffold({
+    Key? key,
+    required this.body,
+    this.appBar,
+  }) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    SystemChrome.setSystemUIOverlayStyle(
+      const SystemUiOverlayStyle(
+        statusBarIconBrightness: Brightness.light,
+        statusBarColor: Colors.transparent,
+        systemNavigationBarContrastEnforced: false,
+        systemNavigationBarColor: Colors.transparent,
+        systemNavigationBarIconBrightness: Brightness.light,
+      ),
+    );
+    return Scaffold(
+      appBar: appBar,
+      extendBodyBehindAppBar: true,
+      body: Container(
+        decoration: const BoxDecoration(
+          image: DecorationImage(
+            fit: BoxFit.cover,
+            image: AssetImage(
+              'assets/login_wallpaper.png',
+            ),
+          ),
+        ),
+        alignment: Alignment.center,
+        child: ConstrainedBox(
+          constraints: const BoxConstraints(maxWidth: 480),
+          child: body,
+        ),
+      ),
+    );
+  }
+}