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>

.github/workflows/ci.yml

@@ -81,7 +81,7 @@ jobs:
     if: needs.changes.outputs.backend == 'true'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: rustfmt
@@ -93,7 +93,7 @@ jobs:
     if: needs.changes.outputs.backend == 'true'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: clippy
@@ -120,7 +120,7 @@ jobs:
           --health-timeout 5s
           --health-retries 5
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2
 
@@ -140,7 +140,7 @@ jobs:
     if: needs.changes.outputs.backend == 'true'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v4
       - uses: rustsec/audit-check@v2.0.0
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
@@ -150,7 +150,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.event_name == 'pull_request'
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2
       - run: cargo build --release