Product data into correct JSON-LD

Product data into correct JSON-LD.

Product and variant data come from the Site API. `/products/<handle>/` publishes a `Product` node with a canonical URL, API description, images, SKU, price, currency and availability from the same variant.

Follow the flow

Read the published product from the Site API, not a hardcoded fixture.
Use the same public URL in `url`, `@id` and `Offer.url`.
Derive `priceCurrency`, `price`, `sku` and `availability` from each API variant.
Keep preview and test catalogs noindex, and omit ratings, brand or return policy when the source does not provide them.

Linking is part of the implementation

The store links to the product URL through `isPartOf`/`WebSite`, while the product links back to the stable store URL. JSON-LD does not copy another customer's product data or add false review or Product schema fields.

The snippet is illustrative; published values come from the Site API.

<script type="application/ld+json">{
  "@context": "https://schema.org",
  "@type": "Product",
  "url": "https://nettbutikk.reai.no/products/test-betaling/",
  "offers": [{ "@type": "Offer", "price": 1, "priceCurrency": "NOK", "availability": "https://schema.org/InStock" }]
}</script>

Next chapterBundles, inventory and pickup. ↗