add-pie-chart-art-component OpenSpec change and document the component scope.src/components/PieChartArt/ with typed defaults, JSON parsing, palette resolution, geometry helpers, label helpers, and safe prop clamping.src/shader/PieChartArt/slice.vert and slice.frag for gradient coloring on WebGL standard materials.PieChartArt in src/dcsConfig.ts with defaults, object transform, and only the requested controls.public/preview/.