Function format_derived_value_cell 

pub fn format_derived_value_cell(
    v: DerivedValue,
    ladder: ScaleLadder,
    is_ratio: bool,
) -> String

Format a derived-metric value cell for the ## Derived metrics table. Ratio rows (is_ratio: true, ScaleLadder::None) render with three decimals (0.873); ns / B / ticks ladders route through the same auto-scale ladder as the main table. Negative values (e.g. a negative live_heap_estimate) carry their explicit minus sign through the format.