Disabling the buy button with a zero balance on the product OpenCart

This small change makes the stock availability check. If the stock balance of a product is less than or equal to zero, all "Add to cart" buttons for such a product will be deactivated/disabled (it will not be possible to add to cart). And instead of the standard text "add to cart" or "buy", the actual state of the products in stock will be displayed. For example, "Pre-order", Out of stock" or "Waiting 2-3 days". Statuses can be edited and created unlimitedly in the localization section of OpenCart.

This ocmod was written to display in standard opencart modules (New Arrivals, Featured, Bestsellers, Promotions), product page, search, category and manufacturer page.