sign method

@override Future<Nip01Event> sign(Nip01Event event)

Signs the given event and returns the signed event

Implementation

@override
Future<Nip01Event> sign(Nip01Event event) async {
  if (privateKey == null || privateKey!.isEmpty) {
    throw Exception('Private key is required for signing');
  }

  final crypto = await _getCrypto();
  final signature = await crypto
      .signEvent(privateKey!.toJS, event.id.toJS)
      .toDart;

  return event.copyWith(sig: signature.toDart);
}