hernoemNode method
Implementation
Future<void> hernoemNode(String nodeId, String naam) async {
final idx = _nodeIdx(nodeId);
if (idx < 0) return;
final updated = List<LeidingNode>.from(_boom!.nodes);
updated[idx] = updated[idx].copyWith(naam: naam.trim());
_boom = _boom!.copyWith(nodes: updated);
notifyListeners();
await _slaOp();
}