✨ feat(SkusContainer): use useSkus hook and remove API calls from SkuReducer

[acasazza]

Summary

Sub-issue of #719.

Replace the manual SDK calls in SkuReducer with the useSkus hook from @commercelayer/hooks, and refactor SkusContainer to use it directly.

Current behaviour

• SkusContainer uses useReducer + getSku from SkuReducer
• SkuReducer calls sdk.skus.list() directly, handling pagination manually
• API logic is duplicated between the reducer and the new hooks package

Expected behaviour

• SkusContainer uses the useSkus hook from @commercelayer/hooks
• SkuReducer no longer contains any API calls — only state shape and pure reducer logic (or is removed entirely if no longer needed)
• Pagination and caching handled by the hook via SWR

Tasks

• Integrate useSkus hook into SkusContainer
• Remove getSku API call from SkuReducer
• Update or remove reducer if state can be derived from the hook
• Update tests

References

• Parent issue: Add SKU resource to core and hooks packages #719
• SkusContainer: packages/react-components/src/components/skus/SkusContainer.tsx
• SkuReducer: packages/react-components/src/reducers/SkuReducer.ts
• useSkus: packages/hooks/src/skus/useSkus.ts