Integration with third-party notification platforms (Infobip, MoEngage)

Allow merchants to send back-in-stock/restock notifications through third-party communication platforms like Infobip or MoEngage instead of (or in addition to) the app's built-in notification system. Use case: Merchant with 4 stores wants to send restock notifications from their own official phone number/sender ID via Infobip, rather than from the app's default sender. This is important for brand consistency and customer trust.