Store API updates

The Store API can now do more for members who run their stores with their own tools:

• Enable, disable or prune out of stock offers for many products in one request, and add a merchant offer from its product ID alone.
• Import a product from any shop's product page link, not only Amazon.
• Create AI articles that stay drafts until the writing finishes. Your edits are kept, and a failed article says why.
• Fill categories with your own search keyword, per category if you like. A fill that is already queued now says so.
• Create categories with AI content and keep the title you gave them.
• Fill missing article images, even when an article has no hero image.
• Import products from a CSV file.
• Custom offers you create show in your store at once, with their pictures.
• Read and set your About you line.
• Set store countries with two letter codes such as us or gb. Codes that are not countries are refused.