Cards fall back to the section image

A card with no image of its own shows the section’s image.

be-best/layouts/_partials/images/featured-image.html:14 falls back to .Parent.Page.Resources when the page has no featured.webp. In a listing, every image-less post therefore renders its section’s image, and the same large file repeats across the page. All 6 cards on public/post/garden/index.html render /post/garden/featured_hu_ecf1cdc248bd6b78.jpg: no garden post in that page carries its own featured.webp. At the 1920w variant the section image weighs 363 KB, so the page requests 2.2 MB of one picture.

Cards fall back to the section image

• A card selects an image from its own page resources only: drop the .Parent.Page.Resources lookup from the card path.
• A card with no image renders text only, with no <img>, no <picture> and no bigImgDiv wrapper.
• The page-level featured image keeps its inherited-image behaviour, documented as intended for post pages.

Acceptance Criteria

• On public/post/garden/index.html, each image URL appears at most once, and the number of card images equals the number of cards whose post owns a featured.webp, 0 on that page today.
• public/post/index.html keeps 6 cards with 6 distinct image URLs.
• No page in public/ repeats the same featured image URL in two cards.
• pnpm run test passes.

Split out from p2-us-featured-images, which covers the sizes hint only.