Account invoice line description

This module adds an option in the Invoicing settings that changes how invoice line descriptions are filled in. When the option "Allow using only the product description on the invoice lines" is enabled, users in the matching group will see the product's description instead of the usual line name.

• For customer invoices and other sale documents, the line description comes from the product's sale description.
• For vendor bills and other purchase documents, it comes from the product's purchase description.
• If the relevant product description is empty, the original line name is kept.

The setting is found in the Invoicing configuration screen and is tied to a hidden user group called "Use only product description on invoice lines". Only users who belong to that group get the new behaviour; other users keep the standard description.

The module extends the invoice line model account.move.line and the settings model res.config.settings. It does not add new menus or reports; it only changes the automatic description text on invoice lines when the option is active.