feat(chart): add @hm-design/chart package with Bar, Line, Donut, Pie, Radar, Area and Radial charts

- new workspace package packages/chart (shadcn/ui Chart + Recharts, HM Theme tokens), examples entry with sample data
- Storybook Chart group (src/chart), consumer example (examples/chart), build:chart / build:chart-example scripts
- README rewritten as the AI usage guide (install, CSS wiring, chart selection, data rules, verification)
- docs: package count/list, Submodule guide (chart workspace, React dedupe), shared AI_GUIDE row, MAINTAINING, story inventory

packages/chart/src/examples/index.ts

@@ -0,0 +1,31 @@
+// Sample data and ready-made example cards. Everything here is illustrative, not business data.
+export { sampleBar, sampleLine, sampleDonut, sampleDonutStates, sampleHorizontalBar, sampleSignedBar, sampleLineCompare, sampleLinePointColors, sampleDataNotice } from "./sample-data"
+export { BarChartExample, StackedBarChartExample, HorizontalBarChartExample, SignedBarChartExample, LineChartExample, LineCurveExample, LineCurveDotLabelExample, LineStraightExample, LineStraightColorLabelExample, LineStepExample, LineStepDotLabelExample, DonutChartExample, DonutPlainExample, DonutCenterExample, DonutActiveExample, DonutInteractiveExample, ChartExamples, SampleDataBadge } from "./chart-examples"
+export { samplePie, sampleStackedPie, sampleRadar } from "./sample-data"
+export {
+  PiePlainExample,
+  PieLabelExample,
+  PieLabelListExample,
+  PieStackedExample,
+  RadarPlainExample,
+  RadarDotExample,
+  RadarLinesOnlyExample,
+  RadarCustomLabelExample,
+  AreaCurveExample,
+  AreaCurveDotLabelExample,
+  AreaStraightExample,
+  AreaStraightColorLabelExample,
+  AreaStepExample,
+  AreaStepDotLabelExample,
+  AreaStackedExample,
+  AreaExpandedExample,
+} from "./pie-radar-area-examples"
+export { sampleRadial, sampleRadialText, sampleRadialShape, sampleRadialStacked } from "./sample-data"
+export {
+  RadialSimpleExample,
+  RadialLabelExample,
+  RadialGridExample,
+  RadialTextExample,
+  RadialShapeExample,
+  RadialStackedExample,
+} from "./radial-examples"