Format a data-unit value for every readout of a unit-bearing layer — the
window's header values, its track bounds and the tooltip — so one value reads
the same everywhere: four significant digits below 1000 ("5.252", "208.9"),
whole numbers with thousands separators from 1000 ("1,597"), scientific
notation at the extremes. Scenes without a unit keep
formatLegacyRangeValue.
Format a data-unit value for every readout of a unit-bearing layer — the window's header values, its track bounds and the tooltip — so one value reads the same everywhere: four significant digits below 1000 ("5.252", "208.9"), whole numbers with thousands separators from 1000 ("1,597"), scientific notation at the extremes. Scenes without a unit keep formatLegacyRangeValue.