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/scenarios/02-folder-management.spec.ts

@@ -73,7 +73,7 @@ test.describe('Folder management', () => {
   });
 
   test('folder creation', async ({ page }) => {
-    const name = `Test folder ${Date.now()}`;
+    const name = `Test folder creation`;
 
     await submitNewFolder(page, name);
 
@@ -92,7 +92,7 @@ test.describe('Folder management', () => {
   });
 
   test('folder reject if already exists', async ({ page }) => {
-    const name = `Test folder ${Date.now()}`;
+    const name = `Test existing folder`;
 
     // Prerequisite: create the folder once successfully.
     await submitNewFolder(page, name);
@@ -122,9 +122,8 @@ test.describe('Folder management', () => {
   });
 
   test('folder rename', async ({ page }) => {
-    const ts = Date.now();
-    const original = `Test folder ${ts}`;
-    const renamed = `Renamed folder ${ts}`;
+    const original = `Test folder`;
+    const renamed = `Renamed folders`;
 
     // Prerequisite: create the folder to rename.
     await submitNewFolder(page, original);