[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/views/stock_picking_views.xml

@@ -25,6 +25,7 @@
             <xpath expr="//field[@name='quantity']" position="before">
                 <field name="sale_ordered_qty" readonly="1" optional="show"
                        column_invisible="context.get('picking_code') == 'incoming'"/>
+                <field name="move_demand_qty" readonly="1" optional="show"/>
             </xpath>
             <xpath expr="//field[@name='quantity']" position="after">
                 <field name="is_collected" widget="boolean_toggle" optional="show"