refactor: Projektstruktur in app/ und backend/ aufgeteilt

app/lib/jobs_route_mixin.dart

@@ -0,0 +1,23 @@
+import 'package:flutter/material.dart';
+import 'navigation_observer.dart';
+
+mixin RouteAwareState<T extends StatefulWidget> on State<T> implements RouteAware {
+  @override
+  void didPopNext() {
+    // When returning to this route, subclasses can override to refresh state.
+  }
+
+  void subscribeRouteAware() {
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      final route = ModalRoute.of(context);
+      if (route != null) {
+        routeObserver.subscribe(this, route);
+      }
+    });
+  }
+
+  void unsubscribeRouteAware() {
+    routeObserver.unsubscribe(this);
+  }
+}
+