[IMP] stock_picking_batch_custom: keep the weighed quantity on the operator view

Basket Assembly is where the reverting quantity was noticed, so it depends
on stock_move_manual_quantity now and its two lists load `picked`: the web
client only saves the fields present in the arch, and without it the
onchange that freezes a hand-typed quantity never reaches the server.

Collecting a line does the same, minus the demand. It is the operator saying
the goods are in the basket, so the quantity has to survive the reservation
engine even when it was never retyped -- but only a quantity typed by hand
says what the demand should become, and a line collected at zero would
otherwise lose its demand and be cancelled on validation.

Drops views/stock_move_line_views.xml on the way. It declared a second
record under the id stock_picking_batch_views.xml already uses, so it was
loaded first and immediately overwritten: dead weight that would have turned
into a duplicate-field view had anyone renamed it.

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

stock_picking_batch_custom/readme/USAGE.rst

@@ -12,3 +12,8 @@ Uso
    hecho y pendiente) y marca el check de recogido consolidado si corresponde.
 
 4. Ordena o agrupa por categoría en cualquiera de las vistas según convenga.
+
+5. La cantidad que teclea el operario (el peso real de la balanza) queda fijada:
+   se marca como *Picked* y ni el planificador ni la validación de otros
+   albaranes vuelven a modificarla. Marcar **Collected** protege igualmente la
+   cantidad de la línea. Ver ``stock_move_manual_quantity``.