Add component tests for EndRunModal, GameGrid, RulesConfiguration, Layout

33 tests covering rendering, user interactions (userEvent clicks), prop
callbacks, filter state, and conditional description text. Adds a
matchMedia stub to the vitest setup file so components importing
useTheme don't throw in jsdom. Also adds actionlint and zizmor
pre-commit hooks for GitHub Actions linting.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/Layout.test.tsx

@@ -0,0 +1,61 @@
+import { render, screen } from '@testing-library/react'
+import userEvent from '@testing-library/user-event'
+import { MemoryRouter } from 'react-router-dom'
+import { Layout } from './Layout'
+
+vi.mock('../hooks/useTheme', () => ({
+  useTheme: () => ({ theme: 'dark' as const, toggle: vi.fn() }),
+}))
+
+function renderLayout(initialPath = '/') {
+  return render(
+    <MemoryRouter initialEntries={[initialPath]}>
+      <Layout />
+    </MemoryRouter>
+  )
+}
+
+describe('Layout', () => {
+  it('renders all desktop navigation links', () => {
+    renderLayout()
+    expect(screen.getAllByRole('link', { name: /new run/i })[0]).toBeInTheDocument()
+    expect(screen.getAllByRole('link', { name: /my runs/i })[0]).toBeInTheDocument()
+    expect(screen.getAllByRole('link', { name: /genlockes/i })[0]).toBeInTheDocument()
+    expect(screen.getAllByRole('link', { name: /stats/i })[0]).toBeInTheDocument()
+    expect(screen.getAllByRole('link', { name: /admin/i })[0]).toBeInTheDocument()
+  })
+
+  it('renders the brand logo link', () => {
+    renderLayout()
+    expect(screen.getByRole('link', { name: /ant/i })).toBeInTheDocument()
+  })
+
+  it('renders the theme toggle button', () => {
+    renderLayout()
+    expect(screen.getAllByRole('button', { name: /switch to light mode/i })[0]).toBeInTheDocument()
+  })
+
+  it('initially hides the mobile dropdown menu', () => {
+    renderLayout()
+    // Mobile menu items exist in DOM but menu is hidden; the mobile dropdown
+    // only appears inside the sm:hidden block after state toggle.
+    // The hamburger button should be present.
+    expect(screen.getByRole('button', { name: /toggle menu/i })).toBeInTheDocument()
+  })
+
+  it('shows the mobile dropdown when the hamburger is clicked', async () => {
+    renderLayout()
+    const hamburger = screen.getByRole('button', { name: /toggle menu/i })
+    await userEvent.click(hamburger)
+    // After click, the menu open state adds a dropdown with nav links
+    // We can verify the menu is open by checking a class change or that
+    // the nav links appear in the mobile dropdown section.
+    // The mobile dropdown renders navLinks in a div inside sm:hidden
+    expect(screen.getAllByRole('link', { name: /my runs/i }).length).toBeGreaterThan(1)
+  })
+
+  it('renders the footer with PokeDB attribution', () => {
+    renderLayout()
+    expect(screen.getByRole('link', { name: /pokedb/i })).toBeInTheDocument()
+  })
+})