test: expand exporter/css/a11y/i18n regressions and add e2e skip-link focus check

components/testUtils/inspectorA11y.ts

@@ -0,0 +1,8 @@
+// Inspector a11y helper: verify input ↔ helptext wiring via aria-describedby
+import { expect } from 'vitest'
+
+export function assertDescribedBy(input: HTMLElement, helpId: string) {
+  expect(input).toHaveAttribute('aria-describedby', helpId)
+  const help = (input.ownerDocument || document).getElementById(helpId)
+  expect(help).not.toBeNull()
+}