Purchase order line stock available

This module adds a read-only column to the product lines of a purchase order that displays the forecasted stock quantity of the selected product. The value is taken from the product's own forecasted quantity, so it always reflects the same number Odoo shows elsewhere for that product.

Where it appears: - On the purchase order form, in the lines list, right after the invoiced quantity column. - The column is optional and shown by default, so users can hide it if they do not need it.

What it changes: - It only adds information; it does not create any check, restriction, automatic action, email or scheduled job. - The quantity is not editable and is not stored separately: it is simply displayed from the product record.

Which areas it touches: - Purchase orders (purchase.order) and their lines (purchase.order.line). - It relies on the product's forecasted quantity, which comes from the stock module.

Because the code is short and limited to a related field and a view change, no other behaviour is added.