Stock reception screen qty by packaging

This is a small glue module that connects two existing features: the reception screen used by warehouse operators and the ability to display quantities by packaging. It does not create any new screen or menu of its own.

What changes for the user:

• On the existing stock reception screen, the list of product lines now shows an extra column with the quantity expressed by packaging (for example, number of boxes or pallets) next to the usual unit of measure column.
• The column appears in the same table where operators already review the products to receive, so no extra navigation is needed.

The module only adds a view extension on the stock.reception.screen model. It does not add any business rule, check, computation, default value, email or scheduled action by itself; those behaviours come from the two modules it depends on (stock_product_qty_by_packaging and stock_reception_screen).

It is installed automatically when both dependency modules are present, so administrators do not need to install it manually. Because the code only contains a view inheritance and no Python models, the visible effect is limited to the extra packaging quantity field shown on the reception screen.