test: add playwright smoke suite

Add playwright.config.ts with webServer configured to run build and
preview on port 4173. Add e2e/smoke.spec.ts with 4 smoke tests:
rel=me anchor presence, all identity links in HTML, canvas and HUD
visibility, and reduced motion fallback rendering.

Restructure App.tsx to render Scroller outside #demo div to fix
selector ambiguity in e2e tests. Add test.exclude to vite.config.ts
to prevent vitest from running playwright tests.

e2e/smoke.spec.ts

@@ -0,0 +1,30 @@
+import { expect, test } from '@playwright/test'
+import { LINKS } from '../src/content/links'
+
+test('raw HTML contains the rel=me anchor (no JS needed)', async ({ request }) => {
+  const res = await request.get('/')
+  const html = await res.text()
+  expect(html).toMatch(
+    /<a[^>]*href="https:\/\/mastodon\.saillant\.cc\/@clement"[^>]*rel="me"/,
+  )
+})
+
+test('raw HTML contains every identity link', async ({ request }) => {
+  const html = await (await request.get('/')).text()
+  for (const l of LINKS) expect(html).toContain(`href="${l.href}"`)
+})
+
+test('the demo boots: canvas mounts and hud shows', async ({ page }) => {
+  await page.goto('/')
+  await expect(page.locator('#demo canvas')).toBeVisible()
+  await expect(page.locator('#tracker')).toBeVisible()
+})
+
+test('reduced motion serves the readable fallback', async ({ browser }) => {
+  const ctx = await browser.newContext({ reducedMotion: 'reduce' })
+  const page = await ctx.newPage()
+  await page.goto('/')
+  await expect(page.locator('#fallback h1')).toBeVisible()
+  await expect(page.locator('#demo canvas')).toHaveCount(0)
+  await ctx.close()
+})

playwright.config.ts

@@ -0,0 +1,11 @@
+import { defineConfig } from '@playwright/test'
+
+export default defineConfig({
+  testDir: 'e2e',
+  use: { baseURL: 'http://localhost:4173' },
+  webServer: {
+    command: 'npm run build && npm run preview',
+    port: 4173,
+    reuseExistingServer: !process.env.CI,
+  },
+})

src/App.tsx

@@ -15,6 +15,7 @@ export default function App() {
   useRideInput()
   const player = useMemo(() => createModPlayer(), [])
   return (
+    <>
       <div id="demo">
         <Canvas
           dpr={0.6}
@@ -31,8 +32,9 @@ export default function App() {
           <Sky />
           <Stops />
         </Canvas>
-      <Scroller />
         <TrackerPanel player={player} />
       </div>
+      <Scroller />
+    </>
   )
 }

vite.config.ts

@@ -47,4 +47,7 @@ export default defineConfig({
     // served straight from node_modules, where the relative lookup works.
     exclude: ['chiptune3'],
   },
+  test: {
+    exclude: ['node_modules', 'dist', 'e2e'],
+  },
 })