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

src/chart/bar-chart.stories.tsx

@@ -0,0 +1,43 @@
+import type { Meta, StoryObj } from "@storybook/react-vite"
+import {
+  BarChartExample,
+  HorizontalBarChartExample,
+  SignedBarChartExample,
+  StackedBarChartExample,
+} from "@hm-design/chart/examples"
+import { StoryPage, StoryPageHeader, StorySection } from "@/components/story-page"
+
+// shadcn/ui Chart (Recharts) with HM tokens, from the public @hm-design/chart entries. All values are sample data.
+// Narrow widths: use the toolbar Viewport presets (HM Mobile · 390). The chart is fluid.
+const meta = {
+  title: "Chart/Bar Chart",
+  parameters: { layout: "fullscreen", controls: { disable: true } },
+} satisfies Meta
+export default meta
+type Story = StoryObj<typeof meta>
+
+export const Bar: Story = {
+  name: "Bar Chart",
+  render: () => (
+    <StoryPage>
+      <StoryPageHeader title="Bar Chart" />
+      {/* Two sections per row from 1024px (HM desktop boundary), one below. Source order is the mobile order; on desktop it reads
+          row by row: Grouped | Horizontal, then Stacked | Positive / Negative. On desktop every row has the same height and each
+          card fills its section, so card tops, bottoms and chart areas line up. */}
+      <div className="grid grid-cols-1 gap-x-6 lg:auto-rows-fr lg:grid-cols-2 *:flex *:min-w-0 *:flex-col [&_.sb-page-section-body]:flex-1">
+        <StorySection title="Grouped">
+          <BarChartExample />
+        </StorySection>
+        <StorySection title="Horizontal">
+          <HorizontalBarChartExample />
+        </StorySection>
+        <StorySection title="Stacked">
+          <StackedBarChartExample />
+        </StorySection>
+        <StorySection title="Positive / Negative">
+          <SignedBarChartExample />
+        </StorySection>
+      </div>
+    </StoryPage>
+  ),
+}