fix(configurator): lot pricing robust in totals + SO-create (not reliant on onchange)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

fusion_plating/fusion_plating_configurator/tests/test_charge_tax_lot.py

@@ -54,3 +54,14 @@ class TestChargeTaxLot(TransactionCase):
         })
         line._onchange_lot_pricing()
         self.assertEqual(line.unit_price, 2.0)
+
+    def test_lot_line_subtotal_uses_lot_total(self):
+        # Even if unit_price wasn't derived (onchange didn't fire), the
+        # summary subtotal uses the flat lot_total for lot-priced lines.
+        wiz = self._make_wizard(tax_id=self.tax13.id)
+        self.env['fp.direct.order.line'].create({
+            'wizard_id': wiz.id, 'quantity': 500, 'lot_total': 1000.0,
+            'is_lot_priced': True, 'unit_price': 0.0,
+        })
+        wiz.invalidate_recordset()
+        self.assertEqual(wiz.total_subtotal, 1000.0)