fixed stalled requests after app resume

lib/api/marianumcloud/talk/talk_api.dart

@@ -12,6 +12,10 @@ import '../nextcloud_ocs.dart';
 import 'talk_error.dart';
 
 abstract class TalkApi<T extends ApiResponse?> {
+  // package:http has no timeout of its own; a request stuck on a dead
+  // connection (e.g. one started right before a suspend) would spin forever.
+  static const Duration _timeout = Duration(seconds: 30);
+
   String path;
   ApiParams? body;
   Map<String, String>? headers;
@@ -35,7 +39,7 @@ abstract class TalkApi<T extends ApiResponse?> {
 
     final data = await sendGuarded(
       'Talk $endpoint',
-      () => request(endpoint, body, mergedHeaders),
+      () => request(endpoint, body, mergedHeaders)?.timeout(_timeout),
     );
     if (data == null) {
       throw const NetworkException(