Stock Picking Put In Pack Restriction

This module gives warehouse managers control over whether destination packages may be used on a given type of transfer.

On each operation type (for example Receipts, Delivery Orders, Internal Transfers) a new field appears on the operation type form, right after the existing option about showing entire packs. It offers three choices: not set (no restriction), "Destination Package Not Allowed", and "Destination Package required".

On a transfer, the same setting is shown read-only, taken from its operation type. If the operation type says packages are not allowed, the Put In Pack button is hidden on that transfer, and trying to put items in a pack is refused with an error message naming the transfer type.

When the transfer is validated, the system checks each line: if packages are not allowed but a destination package was set, validation is blocked with an error; if a package is required but none was set, validation is also blocked with an error. This applies to stock.move.line records through the _action_done method.

The module touches stock.picking.type, stock.picking and stock.move.line, and adds fields to the operation type form and the transfer form.