/**
 * Coerces a cell's raw value to a finite number for gradient interpolation,
 * or `null` when it can't be scored. Dates map to their timestamp so date
 * columns can carry a colour scale just like numeric ones.
 *
 * Only numbers, `Date`s and ISO date strings are scored — anything else is
 * unscorable. Date strings go through `parseISO` so they land on local
 * midnight, matching how the gradient's own thresholds are read.
 */
export default function toNumericGradientValue(value: unknown): number | null;