Wire targeted toast notifications to document status transitions

Adds emit_notification_user() to 7 endpoints so the acting user and
all admins/owners receive a real-time toast on key document actions:
confirm/cancel order, issue/void invoice, confirm return, confirm PO,
receive PO goods. Other staff and viewers are not notified.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/order/api/engine/confirm_order.php

@@ -38,6 +38,7 @@
         $answer['auto_approved'] = $auto_approve;
         $answer['auto_invoice']  = $auto_invoice;
         notify_node('order_updated', [], $company_id);
+        emit_notification_user($company_id, $user_id, 'Order Confirmed', 'The sales order has been confirmed.', 'success');
         if ($auto_invoice) {
             (new UsageGuard($pdo1, $company_id, $packages))->increment();
             notify_node('invoice_updated', [], $company_id);