[IMP] stock_picking_batch_collect: demanded quantity on the move line lists

The move lists already show the demand, the move line ones do not: the
detailed operations of the batch and of the transfer, and the operator
(Basket Assembly) view. Adds a read-only column with the demand of the
line's move, in the unit of the line, next to the ordered quantity.

Closes #21

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

stock_picking_batch_collect/tests/test_picking_collected.py

@@ -110,6 +110,50 @@ class TestPickingCollected(TransactionCase):
         self.assertEqual(move.sale_ordered_qty, 2.0)
         self.assertEqual(move.move_line_ids.sale_ordered_qty, 2.0)
 
+    def test_move_line_demand_follows_the_move(self):
+        picking = self._create_sale_picking(2.0)
+        move = picking.move_ids
+        line = move.move_line_ids
+
+        self.assertEqual(line.move_demand_qty, 2.0)
+
+        gram = self.env.ref("uom.product_uom_gram")
+        line.product_uom_id = gram
+        self.assertEqual(line.move_demand_qty, 2000.0)
+
+        move.product_uom_qty = 3.0
+        self.assertEqual(line.move_demand_qty, 3000.0)
+
+    def test_move_line_demand_without_sale(self):
+        """Unlike the ordered quantity, the demand needs no sale order."""
+        picking = self.env["stock.picking"].create(
+            {
+                "picking_type_id": self.picking_type_out.id,
+                "location_id": self.stock_location.id,
+                "location_dest_id": self.env.ref("stock.stock_location_customers").id,
+                "move_ids": [
+                    Command.create(
+                        {
+                            "name": self.product.name,
+                            "product_id": self.product.id,
+                            "product_uom_qty": 4.0,
+                            "product_uom": self.product.uom_id.id,
+                            "location_id": self.stock_location.id,
+                            "location_dest_id": self.env.ref(
+                                "stock.stock_location_customers"
+                            ).id,
+                        }
+                    )
+                ],
+            }
+        )
+        picking.action_confirm()
+        picking.action_assign()
+        line = picking.move_ids.move_line_ids
+
+        self.assertEqual(line.move_demand_qty, 4.0)
+        self.assertEqual(line.sale_ordered_qty, 0.0)
+
     def test_batch_summary_ordered_quantity(self):
         pickings = self._create_sale_picking(2.0) | self._create_sale_picking(3.0)
         batch = self.env["stock.picking.batch"].create(