fix: Update async handling in send_shop_order_invoice_telegram_task for Celery compatibility

backend/order/tasks.py

@@ -161,8 +161,13 @@ def send_shop_order_invoice_telegram_task(shop_order_id, chat_id, bot_token):
                 caption=f'فاکتور سفارش #{shop_order_id}\n{shop_order.shop.shop_name}'
             )
         
-        # Run async function
+        # Run async function - create new event loop for Celery context
-        asyncio.run(send_invoice())
+        loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(loop)
+        try:
+            loop.run_until_complete(send_invoice())
+        finally:
+            loop.close()
         
         logging.info(f'Successfully sent shop order invoice {shop_order_id} to Telegram chat {chat_id}')
         return f'Invoice sent successfully to chat {chat_id}'