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>
Edouard Vanbelle