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

lib/api/errors/error_mapper.dart

@@ -3,11 +3,14 @@ import 'dart:io';
 
 import 'package:dio/dio.dart';
 import 'package:http/http.dart' as http;
+import 'package:nextcloud/nextcloud.dart';
 
 import '../api_error.dart';
 import '../marianumcloud/talk/talk_error.dart';
 import 'app_exception.dart';
+import 'auth_exception.dart';
 import 'network_exception.dart';
+import 'not_found_exception.dart';
 import 'parse_exception.dart';
 import 'server_exception.dart';
 import 'talk_exception.dart';
@@ -51,6 +54,33 @@ AppException? _dioToAppException(DioException error) {
   }
 }
 
+/// The nextcloud/dynamite clients throw [DynamiteApiException] on non-2xx.
+/// Its toString() dumps every response header, so the details keep only the
+/// status plus a trimmed body preview (same format as the Talk API errors).
+AppException _dynamiteToAppException(DynamiteApiException error) {
+  final status = error.statusCode;
+  final body = error.body.replaceAll(RegExp(r'\s+'), ' ').trim();
+  final preview = body.length > 500 ? '${body.substring(0, 500)}…' : body;
+  final detail = body.isEmpty ? 'HTTP $status' : 'HTTP $status body=$preview';
+  switch (status) {
+    case 401:
+      return AuthException.unauthorized(technicalDetails: detail);
+    case 403:
+      return AuthException.forbidden(technicalDetails: detail);
+    case 404:
+      return NotFoundException(technicalDetails: detail);
+    case 429:
+      return ServerException(
+        statusCode: status,
+        userMessage:
+            'Zu viele Anfragen. Bitte warte einen Moment, bevor du es erneut versuchst.',
+        technicalDetails: detail,
+      );
+    default:
+      return ServerException(statusCode: status, technicalDetails: detail);
+  }
+}
+
 String errorToUserMessage(Object? error, {String fallback = _defaultFallback}) {
   if (error == null) return fallback;
   if (error is AppException) return error.userMessage;
@@ -62,6 +92,10 @@ String errorToUserMessage(Object? error, {String fallback = _defaultFallback}) {
     if (mapped != null) return mapped.userMessage;
   }
 
+  if (error is DynamiteApiException) {
+    return _dynamiteToAppException(error).userMessage;
+  }
+
   if (error is SocketException) {
     return const NetworkException().userMessage;
   }
@@ -92,6 +126,10 @@ String? errorToTechnicalDetails(Object? error) {
     final mapped = _dioToAppException(error);
     if (mapped != null) return mapped.technicalDetails ?? mapped.toString();
   }
+  if (error is DynamiteApiException) {
+    final mapped = _dynamiteToAppException(error);
+    return mapped.technicalDetails ?? mapped.toString();
+  }
   return error.toString();
 }
 
@@ -102,6 +140,9 @@ bool errorAllowsRetry(Object? error) {
     final mapped = _dioToAppException(error);
     if (mapped != null) return mapped.allowRetry;
   }
+  if (error is DynamiteApiException) {
+    return _dynamiteToAppException(error).allowRetry;
+  }
   return true;
 }