[FIX] website_sale: /shop 500 error if category is not model converter

The /shop route can take a `category` argument (a model converter).
  `/shop/category/<model("product.public.category"[..]):category>`

But if that `category` argument is passed through URL query string
(?category=9), it will raise an error when doing
  `category.can_access_from_current_website()`
as it is an integer since it did not went through the model converter

Note: Among probably others, that type of route is used when changing product
      order on shop

Closes #27490, closes #27724