Account Invoice Base Invoicing Mode

This is a base module: on its own it mainly adds settings and background machinery that other invoicing-mode modules build on.

On the customer form, in the Accounting tab, you get two new fields: - Invoicing mode, a choice list that currently only contains "Standard". - One invoice per order, a checkbox that prevents several sales orders from being grouped into a single invoice.

Both settings are commercial fields, so they are shared with the customer's child contacts.

On sales orders, the invoicing mode is taken automatically from the invoice address of the customer, so it follows the customer setting.

The module also changes how invoices are created from sales orders: invoices are prepared separately for each invoice address, and the "one invoice per order" preference of that address decides whether orders are grouped or not.

A helper method can look for sales orders that are still "to invoice" for a given invoicing mode and company, group them by criteria such as customer or payment terms, and schedule the invoice creation as background jobs. Each generated invoice is then posted automatically through a background job, using a dedicated job channel named invoice_validation. From a job you can open the related invoice directly.

No new menu is added; the settings appear inside the existing customer Accounting tab.