Fix CI playwright install, selector injection in A11yParser, and close() race condition

[Copilot]

Playwright Integration tests were failing in CI due to missing browser binary, plus two code-quality issues flagged in review.

Changes

• CI (test.yml): Add bunx playwright install chromium --with-deps before running tests — was the root cause of all 12 Playwright/Workflow Integration test failures.

• A11yParser.ts: Replace document.querySelector(\label[for="${id}"]`)withgetElementsByTagName+htmlFor` property comparison to eliminate CSS selector injection risk from unsanitized element IDs.

  // Before — ID with special chars (e.g. `my.id`) breaks the selector
  const label = document.querySelector(`label[for="${htmlElement.id}"]`);
  
  // After — safe direct property comparison
  const labels = document.getElementsByTagName("label");
  for (let i = 0; i < labels.length; i++) {
    if ((labels[i] as HTMLLabelElement).htmlFor === htmlElement.id) { ... }
  }

• PlaywrightContext.ts: Fix close() so references are cleared before the async close races the timeout — capturing contextRef locally prevents any code path from operating on a null/freed context while a close is still in-flight.

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