[Feature] Migrate Wave 8: Charts (Chart, CountSegmentedChart, PercentagePieChart)

[lizzy-liang-bigstack]

Description

A brief summary to help everyone understand this feature.

CubeChart wraps chart.js/react-chartjs-2 (already present in the package's dependencies, no new packages needed). CubeCountSegmentedChart depends on CubeSegmentedBar (Wave 5).

Migrate each to its Cube* equivalent in @bigstack-oss/cube-ui following the existing pattern: reame, split styles/utils as needed, colocated test, Storybook story, changeset.

Definition of Done (DoD)

A list of technical requirements must be met for completion. These may include, but are not limited to:

• API data conforming to a specified structure.
• An UI delivering defined functionalities.
• Passing all unit tests.
• Passing a code review.

• CubeChart migrated
• CubeCountSegmentedChart migrated
• CubePercentagePieChart migrated
• Each component has a colocated .test.tsx
• Each component has a Storybook story
• Each component is re-exported from src/index.ts
• pnpm lint, pnpm test, and pnpm build are green
• Changeset(s) added covering all 6 components for the next release

Technical Notes

A section for tech leads to to document technical risks and/or any concerns regarding the DoD.

• Feature Owner:
• Frontend:
• Backend:
• Infra:

UI/UX Mockups (Optional)

Links to design prototypes or wireframes (if applicable).

None

Output artifacts (Definition of Done)

Beyond code, docs, and config changes, completing this issue must also deliver:

• Handbook knowledge update — land the durable, team-readable knowledge from this
  work into the bigstack-handbook cubecos kb (kb/cubecos/…) via
  /bigstack-core:save-to-handbook (Topic / Runbook / Known-issue / ADR as fits).