✨ feat(skus): standalone Sku and SkuList components, deprecate containers

[acasazza]

Summary

Implements standalone <Sku> and <SkuList> components that auto-fetch data without requiring container parents. Containers are deprecated but remain fully backwards-compatible.

Changes

@commercelayer/core

• ✨ Add createBatchStore — generic debounced batch store factory

@commercelayer/hooks

• ✨ Add skusBatchStore (uses createBatchStore)
• ✨ Add useSkuList singular hook (SWR-based, fetches single list by ID)
• ♻️ Refactor pricesBatchStore to use createBatchStore
• ♻️ Update useSkus with useSyncExternalStore batching

@commercelayer/react-components

• ✨ Add standalone <Sku> — batches sibling SKU codes into one API request via debounce store
• ♻️ Update <SkuList> — standalone mode auto-fetches list by ID, accepts params/loader props
• ⚠️ Deprecate <SkusContainer>
• ⚠️ Deprecate <SkuListsContainer>

Docs

• 📝 Add standalone usage examples in stories and MDX

Other

• 🤖 Add Copilot cloud agent biome-check postToolUse hook

Usage

// Standalone Sku (preferred)
<CommerceLayer accessToken="...">
  <Sku skuCode="TSHIRTWS000000FFFFFFLXXX">
    <SkuField attribute="name" tagElement="h2" />
  </Sku>
</CommerceLayer>

// Standalone SkuList (preferred)
<CommerceLayer accessToken="...">
  <SkuList id="yZjQIDxrly" params={{ fields: { skus: ["code", "name"] } }}>
    <Skus>
      <SkuField attribute="name" tagElement="h2" />
    </Skus>
  </SkuList>
</CommerceLayer>

Closes #757