Add MaintenancePage to display maintenance message during downtime

mobile-v3/lib/src/app/shared/pages/maintenance_page.dart

@@ -0,0 +1,43 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_svg/flutter_svg.dart';
+
+class MaintenancePage extends StatelessWidget {
+  const MaintenancePage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return LayoutBuilder(
+      builder: (context, constraints) {
+        double maxWidth = constraints.maxWidth;
+        double maxHeight = constraints.maxHeight;
+
+        return Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            SvgPicture.asset(
+              'assets/icons/error_occured.svg',
+              width: maxWidth * 0.5,
+              height: maxWidth * 0.5,
+            ),
+            SizedBox(height: maxHeight * 0.05),
+            Text(
+              "The app is currently under maintenance",
+              style: Theme.of(context).textTheme.headlineLarge!.copyWith(
+                    fontSize: maxWidth * 0.06,
+                    fontWeight: FontWeight.bold,
+                  ),
+            ),
+            SizedBox(height: maxHeight * 0.02),
+            Text(
+              "We're having issues with our network\nno worries, we'll be back up soon.",
+              textAlign: TextAlign.center,
+              style: TextStyle(
+                fontSize: maxWidth * 0.04,
+              ),
+            ),
+          ],
+        );
+      },
+    );
+  }
+}