test(e2e): Add Gallery block front-end delivery spec

[utkarshcloudinary]

Adds a Playwright spec that checks the Cloudinary Gallery block on the front end. It covers the image count, Cloudinary delivery URLs, and a layout change made in the editor.

Approach

• tests/e2e/cloudinary-gallery-delivery.spec.js (@serial, needs CLOUDINARY_E2E_URL):
  • beforeAll uploads 3 images. It syncs them through the plugin's cloudinary/v1/image_data endpoint, which is the same call the block editor makes. Then it publishes a post with a cloudinary/gallery block set to the expanded layout with 3 columns.
  • N images: the widget viewer renders exactly 3 images. Their public IDs match the selected images, and they fit in one row with no carousel or thumbnail strip.
  • Cloudinary URLs: every <img> in the widget, including thumbnails, has a src/srcset on res.cloudinary.com/<cloud_name>/.
  • Layout change: the test opens the post in the block editor and checks that the block is valid. It selects Classic in the Layout panel and saves. On the front end, the markup changes to mode="classic", a carousel viewer, no scroll viewer, and N thumbnails. All URLs are still Cloudinary URLs.
• The spec waits for the widget's own data-test hooks and data-ready="true". It does not use fixed timeouts. The widget loads from product-gallery.cloudinary.com, so its waits allow 30s.
• Moved expectCloudinaryUrl() from the image delivery spec to tests/e2e/utils/delivery.js so both specs share it.

QA notes

• cp .env.example .env and set CLOUDINARY_E2E_URL to a test account.
• npm run env:start, or npx wp-env start --config .wp-env.ci.json for the plain HTTP setup that CI uses.
• npm run test:e2e:serial -- cloudinary-gallery-delivery, or with the CI config: WP_BASE_URL=http://localhost:8889 ./.wp-env/scripts/run-e2e.sh cloudinary-gallery-delivery --workers=1.
• Expect 2 passing tests. cloudinary-image-delivery should still pass.