refactor(web): migrate rag recommendations collapsed storage

[myshkin451]

Summary

• Migrate the workflow block selector RAG recommendations collapsed state to useLocalStorage.
• Remove stale eslint suppressions for the migrated direct localStorage usage.

Refs #36898

Screenshots

Not applicable. This refactor preserves the existing UI behavior.

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

Validation

pnpm --dir web exec eslint --quiet app/components/workflow/block-selector/rag-tool-recommendations/index.tsx
pnpm --dir web test app/components/workflow/block-selector/__tests__
pnpm --dir web type-check
git diff --check