feat(status): add maintenance page for app downtime

- Create a new MaintenancePage widget to display when the app is in maintenance mode
- Use UI kit components for consistent look and feel
- Implement localized strings for headline and subheadline
- Add padding and layout structure using Scaffold

Author: fulleni

lib/status/view/maintenance_page.dart

@@ -0,0 +1,33 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_news_app_mobile_client_full_source_code/l10n/l10n.dart';
+import 'package:ui_kit/ui_kit.dart';
+
+/// A page displayed to the user when the application is in maintenance mode.
+///
+/// This is a simple, static page that informs the user that the app is
+/// temporarily unavailable and asks them to check back later. It's designed
+/// to be displayed globally, blocking access to all other app features.
+class MaintenancePage extends StatelessWidget {
+  /// {@macro maintenance_page}
+  const MaintenancePage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = context.l10n;
+
+    // The Scaffold provides the basic Material Design visual layout structure.
+    return Scaffold(
+      body: Padding(
+        // Use consistent padding from the UI kit.
+        padding: const EdgeInsets.all(AppSpacing.lg),
+        // The InitialStateWidget from the UI kit is reused here to provide a
+        // consistent look and feel for full-screen informational states.
+        child: InitialStateWidget(
+          icon: Icons.build_circle_outlined,
+          headline: l10n.maintenanceHeadline,
+          subheadline: l10n.maintenanceSubheadline,
+        ),
+      ),
+    );
+  }
+}