added support for simultan downloads in files and talk, support for background downloads, enhanced loading in files with retry

test/widget/loadable_state_primary_loading_test.dart

@@ -0,0 +1,54 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/state/app/infrastructure/loadable_state/view/loadable_state_primary_loading.dart';
+
+void main() {
+  Widget wrap(Widget child) => MaterialApp(home: Scaffold(body: child));
+
+  const slowHint = LoadableStatePrimaryLoading.slowHintText;
+
+  testWidgets('shows the slow hint only after the threshold elapses', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      wrap(const LoadableStatePrimaryLoading(visible: true)),
+    );
+
+    expect(find.text(slowHint), findsNothing);
+
+    await tester.pump(const Duration(seconds: 7));
+    expect(find.text(slowHint), findsNothing);
+
+    await tester.pump(const Duration(seconds: 2));
+    expect(find.text(slowHint), findsOneWidget);
+  });
+
+  testWidgets('an explicit statusText takes precedence over the slow hint', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      wrap(
+        const LoadableStatePrimaryLoading(
+          visible: true,
+          statusText: 'Erneuter Versuch (2 von 3) …',
+        ),
+      ),
+    );
+
+    expect(find.text('Erneuter Versuch (2 von 3) …'), findsOneWidget);
+
+    // Even after the slow-hint threshold the explicit status wins.
+    await tester.pump(const Duration(seconds: 9));
+    expect(find.text('Erneuter Versuch (2 von 3) …'), findsOneWidget);
+    expect(find.text(slowHint), findsNothing);
+  });
+
+  testWidgets('does not arm the slow hint while invisible', (tester) async {
+    await tester.pumpWidget(
+      wrap(const LoadableStatePrimaryLoading(visible: false)),
+    );
+
+    await tester.pump(const Duration(seconds: 20));
+    expect(find.text(slowHint), findsNothing);
+  });
+}