Account Invoice Report Lot Expiration Date

When an invoice is printed or previewed, the report already lists the lot or serial numbers of the products being invoiced. This module extends that list with one extra column showing the expiration date of each lot.

• The expiration date comes from the lot record itself, so it is the date stored on the product lot, not a date typed on the invoice.
• The new column is added to the same table that shows lot/serial numbers on the invoice document, and the table width is adjusted so the extra column fits.
• The date is displayed in the user's language and date format.

It works together with the standard stock and product expiry features, so it only shows meaningful values for products that are tracked by lot or serial number and that have an expiration date set. No new menus, buttons or settings are added; the change is visible only on the invoice report. It touches the account.move model to enrich the lot information used by the report.