Add screenshot tests

tests/intro_visual.spec.ts

@@ -0,0 +1,37 @@
+import {expect, test} from '@playwright/test';
+import {blockTracking} from './helpers';
+
+test.describe('Intro page visual validation @visual', () => {
+  test.beforeEach(async ({page, context}) => {
+    await blockTracking(context);
+    await page.goto('/');
+  });
+
+  test('intro-page', async ({page}) => {
+    // Clean dynamic elements right before snapping the screenshot.
+    await page.evaluate(() => {
+      // 1. Overwrite dynamic footer versioning.
+      const versionEl = document.querySelector('.version');
+      if (versionEl) {
+        (versionEl as HTMLElement).innerText =
+          'version: 2026-01-01 00:00 (testcommit)';
+      }
+
+      // 2. Replace dynamic changelog block with static placeholder.
+      const headers = Array.from(document.querySelectorAll('h3'));
+      const whatsNewHeader = headers.find((h) =>
+        h.textContent?.includes("What's new"),
+      );
+      if (whatsNewHeader) {
+        const changelogSpan = whatsNewHeader.nextElementSibling;
+        if (changelogSpan) {
+          changelogSpan.innerHTML =
+            '<h4>2026-01-01</h4><ul><li>Placeholder change entry</li></ul>';
+        }
+      }
+    });
+
+    // Snap the screenshot.
+    await expect(page).toHaveScreenshot('intro-page.png');
+  });
+});