ci: align E2E workflow Node version to 22 (#17)

The CI and release workflows use Node 22, but E2E was still on Node 20.
This aligns all workflows to the same Node version for consistency.

Co-authored-by: gandalf-the-greybeard[bot] <gandalf-the-greybeard[bot]@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/e2e.yaml

@@ -19,7 +19,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: '20'
+          node-version: '22'
           cache: 'npm'
 
       - name: Install dependencies