Add ARIA tab semantics to BatchOperationsPanel

[kanweiwei]

The BatchOperationsPanel component (web/src/components/batch-operations/BatchOperationsPanel.tsx lines 412-424) uses <button> elements as tabs but lacks proper ARIA semantics for screen readers.

What to do:

1. Read web/src/components/batch-operations/BatchOperationsPanel.tsx
2. Add role="tablist" to the tab container
3. Add role="tab" and aria-selected={isActive} to each tab button
4. Add role="tabpanel" to the tab content panels
5. Add aria-controls and aria-labelledby to link tabs and panels
6. Verify with keyboard navigation (arrow keys between tabs)
7. Run: pnpm -C web run typecheck

Skills needed: HTML accessibility, React, TypeScript

Estimated time: 30 minutes

[snakefood3232]

The BatchOperationsPanel uses button elements as tabs without proper ARIA roles. I'd handle this by adding the required role="tablist", role="tab", and role="tabpanel" attributes with correct aria-selected and linking attributes, plus keyboard navigation. I can have a PR up in a few hours—I regularly implement accessible tab components in TypeScript/React.