Pure extraction core for bar charts: reads D3-bound data under root and
builds the MAIDR layer, without wrapping it in a figure or touching
maidr-data. Used by bindD3Bar (root = the SVG) and by the
multi-panel binders in binders/subplots.ts (root = one panel element,
with panel scoping the emitted selectors to that panel).
Pure extraction core for bar charts: reads D3-bound data under
rootand builds the MAIDR layer, without wrapping it in a figure or touchingmaidr-data. Used by bindD3Bar (root = the SVG) and by the multi-panel binders inbinders/subplots.ts(root = one panel element, withpanelscoping the emitted selectors to that panel).