Expand frontend test coverage for role-based admin routing and shared UI primitives

[Copilot]

This PR addresses coverage gaps in the frontend by adding tests for previously untested route-selection logic and reusable presentation components. It improves confidence in role-gated navigation and shared UI behavior without changing production code.

• Admin entry routing coverage

  • Added frontend/src/admin/AdminApp.test.tsx to exercise /admin landing behavior by role:
    • author roles (researcher/admin) render survey list
    • reviewer redirects to PII review
    • analyst redirects to My DB access
    • unknown role sets hit the fallback path
  • Added explicit coverage for the open login route (/admin/login).

• Respondent shell coverage

  • Added frontend/src/RespondentLayout.test.tsx to verify branded shell rendering (header + content slot).

• Shared UI primitive coverage

  • Added frontend/src/ui/Primitives.test.tsx covering:
    • Alert ARIA role behavior across tones (alert vs status)
    • Card/CardBody content and class passthrough
    • Field label-input association and hint rendering
    • PageHeader title/subtitle/actions rendering contract

it('redirects reviewers to the pii review queue', async () => {
  setRoles(['reviewer']);
  renderAt('/admin');
  expect(await screen.findByText('PII review view')).toBeInTheDocument();
});

[Copilot]

Pull request overview

This PR expands Vitest/Testing Library coverage for the frontend’s role-gated /admin entry routing and a handful of shared UI primitives, improving confidence in navigation and accessibility behavior without changing production components.

Changes:

• Add AdminApp route-selection tests covering /admin landing behavior for author/reviewer/analyst/unknown roles, plus /admin/login.
• Add a RespondentLayout shell rendering test (header + content slot).
• Add UI primitive tests for Alert, Card/CardBody, Field, and PageHeader (including ARIA roles and label association).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
frontend/src/admin/AdminApp.test.tsx	Adds routing/redirect coverage for /admin and the open /admin/login route based on user roles.
frontend/src/RespondentLayout.test.tsx	Verifies the respondent-facing layout renders the branded header and children content.
frontend/src/ui/Primitives.test.tsx	Adds focused tests for shared UI components, including ARIA role expectations and label↔input association.