Initial commit: MeshCore Open Flutter client

Open-source Flutter client for MeshCore LoRa mesh networking devices.

Features:
- BLE device scanning and connection
- Nordic UART Service (NUS) integration
- Material 3 design with system theme support
- Provider-based state management
- Placeholder screens for chat, contacts, and settings

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

test/widget_test.dart

@@ -0,0 +1,12 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:meshcore_open/main.dart';
+
+void main() {
+  testWidgets('App loads successfully', (WidgetTester tester) async {
+    // Build our app and trigger a frame.
+    await tester.pumpWidget(const MeshCoreApp());
+
+    // Verify that the app title appears
+    expect(find.text('MeshCore Open'), findsOneWidget);
+  });
+}