D3 v5 Zoomable Sunburst
This zoomable sunburst chart displays hierarchical data as concentric arcs, where clicking a segment zooms in to show its children while the central circle returns to the root. Built with D3 v5, it uses `d3.hierarchy`, `d3.partition`, and `d3.arc` to render the SVG layout, with `transition.attrTween` animating arc positions and label transforms. The visualization loads the flare dataset via Observable’s stdlib and applies a rainbow color scale based on top-level categories.