feat(fusion_claims): allow order-less tasks + service-repair SO flag

Relaxes _check_order_link to a no-op (service bookings auto-create their SO;
in-shop/walk-in tasks may have none) and adds x_fc_is_service_repair on
sale.order. The 'Service Repair' crm.tag from the plan is intentionally
omitted: fusion_claims does not depend on crm and sale.order has no tag_ids;
the boolean flag is the repair-SO identity.

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

fusion_claims/tests/__init__.py

@@ -4,3 +4,4 @@ from . import test_signed_pages_gate
 from . import test_application_received_wizard
 from . import test_dashboard
 from . import test_service_rate
+from . import test_service_booking