POS Remove POS Category

In standard Odoo, Point of Sale uses its own category list, separate from product categories. This module removes that duplication: the POS now reads the normal product categories, and the old POS category field on products is hidden.

What changes for users: - On each product category you get a new checkbox "Available in the Point of Sale". Only checked categories appear in the POS. If you uncheck a parent category, its children also disappear from the POS, whatever their own checkbox says. - You can add an image to a product category; that image is shown in the POS category buttons. - The category list view shows an "Available in POS" column, and the category form shows the image and the checkbox. - The old "POS Category" field on the product form is hidden, and the POS category menu action now opens the standard product categories.

Automatic behaviour: the POS category of a product is kept in line with its product category when the product is created, and the POS only loads categories marked as available. If the module is uninstalled, the system restores the original link between products and the old POS categories.