find method
Returns the node with id, or null.
Implementation
@override
Future<NodeDescriptor?> find(NodeId id) async {
final rows = db.select('SELECT data FROM nodes WHERE id = ?', [id.value]);
if (rows.isEmpty) return null;
return NodeDescriptor.fromJson(
jsonDecode(rows.first['data'] as String) as Map<String, dynamic>,
);
}