migrated Marianum Message module to the Marianum-Connect API and implemented push notification deep linking

lib/api/marianumconnect/queries/get_newsletter_file/get_newsletter_file.dart

@@ -0,0 +1,34 @@
+import 'dart:typed_data';
+
+import 'package:dio/dio.dart';
+
+import '../../errors/marianumconnect_error.dart';
+import '../../marianumconnect_api.dart';
+import '../../marianumconnect_endpoint.dart';
+
+/// Downloads the raw PDF bytes of a Marianum Message from
+/// `GET /api/mobile/v1/newsletter/{id}/file`.
+///
+/// Goes through the shared MC dio so the bearer token is attached automatically;
+/// the bytes are handed to `SfPdfViewer.memory` so no auth header has to be
+/// plumbed into the viewer itself.
+class GetNewsletterFile {
+  final String id;
+  final Dio _dio;
+
+  GetNewsletterFile(this.id, {Dio? dio}) : _dio = dio ?? MarianumConnectApi.dio();
+
+  Future<Uint8List> run() async {
+    try {
+      final response = await _dio.get<List<int>>(
+        MarianumConnectEndpoint.resolve(
+          'newsletter/${Uri.encodeComponent(id)}/file',
+        ),
+        options: Options(responseType: ResponseType.bytes),
+      );
+      return Uint8List.fromList(response.data!);
+    } on DioException catch (e) {
+      throw mapMarianumConnectError(e);
+    }
+  }
+}