refactor: Projektstruktur in app/ und backend/ aufgeteilt

app/lib/services/dart_mq.dart

@@ -0,0 +1,100 @@
+import 'package:votianlt_app/services/developer.dart' as developer;
+
+/// A lightweight in-app message bus ("dart_mq") for pub/sub style communication.
+///
+// Usage:
+//   final mq = DartMQ();
+//   final sub = mq.subscribe<bool>('connection/status', (isOnline) { /* ... */ });
+//   mq.publish('connection/status', true);
+//   sub.cancel();
+class DartMQ {
+  DartMQ._internal();
+  static final DartMQ _instance = DartMQ._internal();
+  factory DartMQ() => _instance;
+
+  final Map<String, List<_DartMQSubscriber>> _subscribers = {};
+
+  /// Subscribe to a topic. Returns a cancellable subscription handle.
+  DartMQSubscription subscribe<T>(String topic, void Function(T data) handler) {
+    final sub = _DartMQSubscriber<T>(topic: topic, handler: handler);
+    final list = _subscribers.putIfAbsent(topic, () => <_DartMQSubscriber>[]);
+    list.add(sub);
+    return DartMQSubscription._(this, sub);
+  }
+
+  /// Publish a message to a topic. If no subscribers exist, this is a no-op.
+  void publish<T>(String topic, T data) {
+    final list = _subscribers[topic];
+    if (list == null || list.isEmpty) return;
+
+    // Make a defensive copy to allow cancellation during iteration.
+    final current = List<_DartMQSubscriber>.from(list);
+    for (final s in current) {
+      // Only deliver if types match; otherwise, try dynamic fallback
+      if (s is _DartMQSubscriber<T>) {
+        try {
+          s.handler(data);
+        } catch (e, stackTrace) {
+          developer.log(
+            'Error delivering message to subscriber on topic "$topic": $e',
+          );
+          developer.log('Stack trace: $stackTrace');
+        }
+      } else {
+        // Fallback delivery for handlers expecting dynamic or different T
+        try {
+          final dynamicHandler = s.handler as dynamic;
+          dynamicHandler(data);
+        } catch (e, stackTrace) {
+          developer.log(
+            'Error delivering dynamic message to subscriber on topic "$topic": $e',
+          );
+          developer.log('Stack trace: $stackTrace');
+        }
+      }
+    }
+  }
+
+  void _cancel(_DartMQSubscriber subscriber) {
+    final list = _subscribers[subscriber.topic];
+    if (list == null) return;
+    list.remove(subscriber);
+    if (list.isEmpty) {
+      _subscribers.remove(subscriber.topic);
+    }
+  }
+}
+
+/// Cancellable subscription handle
+class DartMQSubscription {
+  final DartMQ _mq;
+  final _DartMQSubscriber _subscriber;
+  bool _isCancelled = false;
+
+  DartMQSubscription._(this._mq, this._subscriber);
+
+  void cancel() {
+    if (_isCancelled) return;
+    _isCancelled = true;
+    _mq._cancel(_subscriber);
+  }
+}
+
+class _DartMQSubscriber<T> {
+  final String topic;
+  final void Function(T data) handler;
+  _DartMQSubscriber({required this.topic, required this.handler});
+}
+
+/// Common topics used in the app
+class MQTopics {
+  static const connectionStatus = 'connection/status'; // bool
+  static const authResponse = 'auth/response'; // Map<String, dynamic>
+  static const jobsResponse = 'jobs/response'; // List<dynamic>
+  static const taskEvents = 'task/events'; // Map<String, dynamic>
+  static const jobsUpdated = 'app/jobsUpdated'; // void/null
+  static const jobDeleted = 'job/deleted'; // Map<String, dynamic> {jobId, jobNumber, deletedAt}
+  static const jobCreated = 'job/created'; // Map<String, dynamic> - full job data
+  static const chatIncoming = 'chat/incoming'; // ChatMessage
+  static const chatOutgoing = 'chat/outgoing'; // ChatMessage
+}