Implement Standalone Android App via Flutter WebView

- Configured `vite.config.ts` for relative base path support.
- Initialized `mobile_app` Flutter project with `webview_flutter`.
- Added `assets/www` to Flutter assets configuration.
- Implemented `mobile_app/lib/main.dart` with WebView and Bridge API integration (Water Level Slider).
- Updated `.gitignore` for Flutter artifacts.
- Successfully built APK artifacts.

Co-authored-by: kliffdafunkfacekilla-arch <239708976+kliffdafunkfacekilla-arch@users.noreply.github.com>

mobile_app/test/widget_test.dart

@@ -0,0 +1,30 @@
+// This is a basic Flutter widget test.
+//
+// To perform an interaction with a widget in your test, use the WidgetTester
+// utility in the flutter_test package. For example, you can send tap and scroll
+// gestures. You can also use WidgetTester to find child widgets in the widget
+// tree, read text, and verify that the values of widget properties are correct.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:mobile_app/main.dart';
+
+void main() {
+  testWidgets('Counter increments smoke test', (WidgetTester tester) async {
+    // Build our app and trigger a frame.
+    await tester.pumpWidget(const MyApp());
+
+    // Verify that our counter starts at 0.
+    expect(find.text('0'), findsOneWidget);
+    expect(find.text('1'), findsNothing);
+
+    // Tap the '+' icon and trigger a frame.
+    await tester.tap(find.byIcon(Icons.add));
+    await tester.pump();
+
+    // Verify that our counter has incremented.
+    expect(find.text('0'), findsNothing);
+    expect(find.text('1'), findsOneWidget);
+  });
+}