[FIX] sale_order_type_invoice_policy_invoice_link: replace process-wide monkey patch with model inheritance

[gal-adhoc]

Problem

models/stock_move.py patched stock_picking_invoice_link's StockMove.write at import time:

from odoo.addons.stock_picking_invoice_link.models.stock_move import StockMove
def new_write(self, vals): ...
StockMove.write = new_write

That mutates the class object for the whole Odoo process, and nothing ever undoes it. Uninstalling this module removes its models from the registry but does not un-import the Python module nor restore the original write. The patched body reads sale_line_id.order_id.type_id.invoice_policy, a field contributed by sale_order_type_invoice_policy, so once that field is gone every picking validation crashes until the worker is restarted.

Reproduced on a production database:

1. Install sale_order_type_invoice_policy — sale_order_type_invoice_policy_invoice_link auto-installs and the patch is applied to the class.
2. Uninstall it ~45 seconds later. The registry reloads without sale.order.type.invoice_policy, but the patched write is still in place.
3. Validate any delivery, the next day, on the same worker:

File ".../stock/models/stock_move.py", line 2111, in _action_done
    moves_todo.write({'state': 'done', 'date': fields.Datetime.now()})
File ".../sale_order_type_invoice_policy_invoice_link/models/stock_move.py", line 16, in new_write
    invoice_policy = stock_move.sudo().sale_line_id.order_id.type_id.invoice_policy
AttributeError: 'sale.order.type' object has no attribute 'invoice_policy'

23 consecutive failures over ~50 minutes, from a module that was not installed on that database.

Fix

Use a regular _inherit = "stock.move" override. The code then lives in the registry instead of in the class object, so it is present exactly when the module is installed and gone as soon as it is uninstalled. That removes the whole class of failure rather than guarding against this one symptom.

Also drops the duplicated You can not modify an invoiced stock move check: the monkey patch had to reimplement it because it was replacing stock_picking_invoice_link.write. With normal inheritance that check runs through super() again.

Business logic is unchanged — invoice lines are still linked when the sale order type policy is order, or when it is by_product and the product policy is order.

Test plan

• With sale_order_type_invoice_policy and this module installed: create a sale.order.type with invoice_policy = 'order', confirm a SO with that type, invoice it, validate the delivery, and check stock.move.invoice_line_ids is populated. Same behaviour as before.
• Install both modules, uninstall them, then validate a delivery without restarting the worker: no longer raises AttributeError. This is the regression that motivated the change.
• Modifying product_uom_qty on a done move that has linked invoice lines still raises the UserError.

Ref: https://www.adhoc.inc/odoo/helpdesk.ticket/124767

[roboadhoc]