test(playwright): add playwright report to track changes + correct playwright parameters

ci: fix actions/checkout@v6 → @v4 (v6 does not exist)

GitHub started rejecting invalid action versions at parse time,
causing every CI run to fail with 0s / 'workflow file issue'
before any jobs could start.

 * test(e2e): only no retry
 * test(e2e): use static name in tests to facilitate screenshot comparaison
 * test(e2e): update linux screenshots
 * test(e2e): adapt test due to user-vignette generation

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

tests/e2e/playwright.config.ts

@@ -27,9 +27,9 @@ export default defineConfig({
   testDir: './scenarios',
   fullyParallel: false,
   forbidOnly: !!process.env.CI,
-  retries: process.env.CI ? 2 : 0,
+  retries: 0,
   workers: 1,
-  reporter: process.env.CI ? [['github'], ['html']] : 'html',
+  reporter: process.env.CI ? [['line'], ['github'], ['html']] : [ ['list'], ['html']],
 
   globalSetup: require.resolve('./global-setup'),
   globalTeardown: require.resolve('./global-teardown'),
@@ -37,6 +37,9 @@ export default defineConfig({
   use: {
     baseURL: 'http://localhost:8087',
     trace: 'on-first-retry',
+    headless: true,
+    // take a screenshot on failure
+    screenshot: 'only-on-failure',
   },
 
   expect: {