Wishlist management

[faid-terence]

Adding items to a wishlist is a common feature for e-commerce websites, as it allows buyers to save items for later consideration or purchase.

GIVEN that the buyer is on a product page

WHEN the buyer clicks the ""Add to Wishlist"" button or a button to add the item to the wishlist without leaving the current page (optional)
THEN the item should be added to the buyer's wishlist and the buyer should see a confirmation message
Dev notes:

The ""Add to Wishlist"" button should be disabled if the buyer is not logged in.
The optional feature to add the item to the wishlist without leaving the current page should be implemented using an overlay or a modal window.