Add Flutter project skeleton (Android-only MVP)

Five-layer architecture per DMC_Architektur_und_Design.md: FlightControllerLink
abstraction (Mock + MSP stub), protocol-neutral mission domain layer, App-Mode
state machine with Ready-to-Fly gate, Drift persistence schema, and placeholder
UI screens wired via go_router. App icon generated from design/Y2_pink_dark.svg.
Verified with flutter analyze and flutter test.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/lib/transport/msp/msp_flight_controller_link.dart

@@ -0,0 +1,39 @@
+import '../../domain/waypoint/flat_waypoint_list.dart';
+import '../flight_controller_link.dart';
+
+/// iNAV-Anbindung via MSP (Architektur-Doku 3.1). Eigenstaendiger Adapter,
+/// da kein fertiges Dart-Paket fuer MSP verfuegbar ist (Doku 4.19).
+///
+/// Protokoll-Implementierung (Framing, MSP_SET_WP, MSP_NAV_STATUS, ...) ist
+/// noch offen - dies ist bewusst nur das Geruest fuer die Abstraktion.
+class MspFlightControllerLink implements FlightControllerLink {
+  MspFlightControllerLink({required this.host, required this.port});
+
+  final String host;
+  final int port;
+
+  @override
+  FcCapabilities get capabilities => throw UnimplementedError();
+
+  @override
+  Future<void> connect() => throw UnimplementedError();
+
+  @override
+  Future<void> disconnect() => throw UnimplementedError();
+
+  @override
+  Future<void> uploadMission(FlatWaypointList mission) =>
+      throw UnimplementedError();
+
+  @override
+  Future<void> setFlightMode(FlightMode mode) => throw UnimplementedError();
+
+  @override
+  Future<void> arm() => throw UnimplementedError();
+
+  @override
+  Stream<TelemetryFrame> subscribeTelemetry() => throw UnimplementedError();
+
+  @override
+  Future<int?> readActiveWaypointIndex() => throw UnimplementedError();
+}