Fix: добавлен импорт get_object_or_404 в pos/views.py

Исправлена ошибка 'get_object_or_404 is not defined' при попытке
провести оплату через POS-терминал.

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

myproject/pos/views.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-from django.shortcuts import render
+from django.shortcuts import render, get_object_or_404
 from django.contrib.auth.decorators import login_required
 from django.http import JsonResponse
 from django.views.decorators.http import require_http_methods