Enable diff review mode in test workflow

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

Author: ritikrishu

.github/workflows/test-action.yml

@@ -24,5 +24,6 @@ jobs:
           renderer: service
           service-url: https://pencil.remotestate.com
           service-api-key: ${{ secrets.SCREENSHOT_API_KEY }}
+          review-mode: diff
           image-format: webp
           image-scale: 3