Flutter-App mit WebView, STOMP-Client und Konfigurationssystem

- Flutter-App (app/) für iOS, Android, macOS, Windows und Linux erstellt
- WebView-Startseite mit flutter_inappwebview (iOS/Android/macOS/Windows),
  Linux-Fallback mit url_launcher
- STOMP-over-WebSocket: Topic-basierte Echtzeit-Kommunikation zwischen
  Flutter-App und Spring Boot Core
- Core: STOMP-Broker (/ws/stomp), CallEventBroadcaster auf /topic/calls,
  StompMessageController für /app/ping und /app/broadcast
- SecurityConfig: /ws/** permitAll + CSRF-Ausnahme
- Asset-basierte Konfigurationsdatei (app_config.json) für Server-URL,
  STOMP-Reconnect, Topics und WebView-URL
- launch.json um Flutter-Debug/Profile/Release-Konfigurationen erweitert
- macOS: FLTEnableMergedPlatformUIThread deaktiviert (WKWebView-Kompatibilität),
  network.client Entitlement gesetzt
- iOS: NSAllowsLocalNetworking für lokale Entwicklung
- Android: INTERNET-Permission und usesCleartextTraffic

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/lib/config/app_config.dart

@@ -0,0 +1,46 @@
+import 'dart:convert';
+
+import 'package:flutter/services.dart' show rootBundle;
+
+class AppConfig {
+  static const String _assetPath = 'assets/config/app_config.json';
+
+  final String stompUrl;
+  final Duration reconnectDelay;
+  final String webviewUrl;
+  final String defaultTopic;
+  final List<String> topicPresets;
+  final String defaultDestination;
+  final String defaultPayload;
+
+  const AppConfig({
+    required this.stompUrl,
+    required this.reconnectDelay,
+    required this.webviewUrl,
+    required this.defaultTopic,
+    required this.topicPresets,
+    required this.defaultDestination,
+    required this.defaultPayload,
+  });
+
+  static Future<AppConfig> load() async {
+    final raw = await rootBundle.loadString(_assetPath);
+    final json = jsonDecode(raw) as Map<String, dynamic>;
+    final server = json['server'] as Map<String, dynamic>;
+    final topics = json['topics'] as Map<String, dynamic>;
+    final send = json['send'] as Map<String, dynamic>;
+
+    return AppConfig(
+      stompUrl: server['stompUrl'] as String,
+      reconnectDelay: Duration(
+        seconds: (server['reconnectDelaySeconds'] as num).toInt(),
+      ),
+      webviewUrl: server['webviewUrl'] as String,
+      defaultTopic: topics['default'] as String,
+      topicPresets: (topics['presets'] as List).cast<String>(),
+      defaultDestination: send['defaultDestination'] as String,
+      defaultPayload:
+          const JsonEncoder.withIndent('  ').convert(send['defaultPayload']),
+    );
+  }
+}