/// «12,3 тыс», «1,2 млн» — for axis labels and cells too narrow for a full amount.
///
/// fl_chart's own short form («414.6K») is English and rounds a step of 50 000 to the same
/// label twice; this one keeps the Russian suffixes and one decimal below a hundred.
String compactNumber(double value) {
  final n = value.abs();
  String scaled(double x, String suffix) {
    final s = x >= 100
        ? x.round().toString()
        : x.toStringAsFixed(1).replaceAll(RegExp(r'\.0$'), '');
    return '${s.replaceAll('.', ',')} $suffix';
  }

  final sign = value < 0 ? '−' : '';
  if (n >= 1e6) return '$sign${scaled(n / 1e6, 'млн')}';
  if (n >= 1e3) return '$sign${scaled(n / 1e3, 'тыс')}';
  return '$sign${n.round()}';
}