processPushMessage method
Decrypt an FCM/APNs push payload for an existing conversation (looked up by topic).
Returns a list of decoded messages — usually 1, occasionally more if the
envelope contained multiple. Each entry mirrors getMessagesAfterDate shape.
Implementation
@override
Future<List<Map<String, dynamic>>> processPushMessage(
String topic, Uint8List encryptedBytes) {
throw UnimplementedError(
'processPushMessage() is not implemented on Web. FCM web-push is out of scope; use the Android/iOS clients for push notifications.');
}