fix(playwright): wait for header-toggle-all attached, not visible

The antd Checkbox spreads `data-test` onto its inner <input>, which
renders with opacity:0 and a zero bounding box and therefore never
satisfies Playwright's visibility check. Every E2E run on this branch
has timed out at this wait. Switching to `state: 'attached'` preserves
the original intent (signal that the bulk-select column has rendered)
without tripping the visibility trap.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>