feat(reports): packing slip for local deliveries (fusion.plating.delivery)

The packing slip report only existed for stock.picking (Delivery Orders),
but this shop ships via fusion.plating.delivery and has no pickings — so
packing slips never rendered for their flow, and the prior auto-generate +
email-notification paths pointed the stock.picking report at a delivery
(wrong model -> blank PDF).

Add a delivery-native variant: report_fp_packing_slip_delivery_portrait +
action_report_fp_packing_slip_delivery_portrait (bound to
fusion.plating.delivery -> shows in the delivery Print menu), resolving the
SO + lines from the delivery job_ref (same pattern as the BoL report) and
reusing the shared styles / address / signoff bits + a sale.order.line
items table. Repoint _fp_generate_packing_slip (dispatch auto-gen) and the
notification attachment to the new report.

Verified on entech: real content (customer, PO, items, PS#) for DLV-30102 —
142KB PDF vs prior blank 12.8KB.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating_notifications/models/fp_notification_template.py

@@ -377,7 +377,7 @@ class FpNotificationTemplate(models.Model):
         # Packing slip — gated by customer preference (default True)
         if self.attach_packing_list and delivery and _customer_wants('x_fc_send_packing_slip'):
             att = _render_report(
-                'fusion_plating_reports.action_report_fp_packing_slip_portrait', delivery,
+                'fusion_plating_reports.action_report_fp_packing_slip_delivery_portrait', delivery,
             )
             if att:
                 ids.append(att)