Stock archive constraint

This module adds safety checks to the standard archiving action (the "Archive" toggle) in Odoo's Inventory app. It does not add new menus or screens; it simply blocks archiving when it would be unsafe.

For products, archiving is refused when: - The product still has a non-zero quantity in internal or transit locations (stock on hand). - The product appears on stock moves that are not yet done or cancelled (open transfers). - The product appears on stock move lines that are not yet done or cancelled (open reservations).

For storage locations, archiving is refused when the location (or any of its child locations) is used as source or destination on stock moves or stock move lines that are not yet done or cancelled.

When a check fails, Odoo raises a validation error naming the product or location, so the user knows exactly why archiving was blocked. The checks run automatically whenever the active flag is changed on product.product or stock.location. No new fields, reports, emails or scheduled jobs are added.