D3 v5 Zoomable Sunburst
A zoomable sunburst chart displays hierarchical data as concentric arcs, where clicking a segment zooms in to show it as the new root. Built with D3 v5, it uses `d3.hierarchy`, `d3.partition`, and `d3.arc` to compute and render the layout, with a color scale based on `d3.interpolateRainbow`. Clicking triggers a smooth 750ms transition via `transition.attrTween`, animating arc paths and labels. The hierarchy comes from the Observable `@observablehq/flare` dataset, rendered as SVG with interactive hover tooltips.