Function balance_chart 

pub fn balance_chart(
    rows: &[ReportRowView],
    opts: BalanceChartOpts,
) -> ChartSpec

Balance chart: one series per commodity, x = top-level account names. When more than one commodity is present and the top_n most-active accounts span several commodities, we still render all bars — each series places a bar in the x-slot for its account and zero elsewhere, so a mixed-currency report reads as a grouped / stacked bar chart.