[IMP] stock_picking_batch_custom: allow deleting operator lines, show picking reference

Allow removing stock.move.line records from the Basket Assembly operator
view (select + Delete action) instead of forcing quantity to zero, which
caused issues for operators. Also expose the picking reference field
(hidden by default) before the contact column.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

stock_picking_batch_custom/models/stock_picking_batch.py

@@ -239,7 +239,7 @@ class StockPickingBatch(models.Model):
             "domain": [("batch_id", "=", self.id)],
             "context": {
                 "create": False,
-                "delete": False,
+                "delete": True,
             },
         }