Stock Move picking assignment hook

This is a technical base module for developers and integrators. It does not add any new menu, screen, button or report, and it does not change what users see in the standard Odoo interface.

What it does: when Odoo needs to find an existing transfer (a stock.picking) to attach a stock move to, the module replaces the built-in search with a method that can be overridden. The default search still uses the usual criteria: same procurement group, same source location, same destination location, same operation type, not yet printed, not an immediate transfer, and in a state among draft, confirmed, waiting, partially available or assigned.

Because the search is now split into separate methods, other modules can change the search rules or the search domain without copying the whole standard code. This makes custom warehouse flows easier to maintain and upgrade.

It touches the stock.move model only. No scheduled jobs, emails, checks or computed fields are added. The module is marked Production/Stable and depends on the standard Inventory (stock) app.