Enable Add to cart endpoint to work after place order

[Add to cart endpoint](https://docs.zid.sa/docs/zid-themes-api-library/skcxlth80xxlh-cart-functions-in-zid-themes-library#add-product-to-cart) does work only inside theme laibrary, and doesn't with placed order page "the latest page after placed order" It's useful function for post purchase upsell.