PivotRowRole
type PivotRowRole = { kind: "subheading" | "subtotal"; level?: number; row: number;};The style role of one pivot output row that styles differently from a plain data row, identified
by its 0-based row offset from the top of the pivot’s ref:
subheading: a row-axis group label row (outline/tabular layout).subtotal: a row-axis subtotal row.
Page-field (report filter) cells are not row roles: they sit above and outside ref and are
styled from the pivot’s pageArea geometry instead (with the pageFieldLabels /
pageFieldValues regions).