Ability to receive external webhooks (e.g. purchase confirmation on external platform)#2629

Description / Use case:
Currently, FunnelCore can only send webhooks to external tools, but it cannot receive them.
A very useful feature would be the ability to receive a webhook from an external platform (like Hotmart) and automatically trigger actions inside FunnelCore, such as assigning a tag or adding the user to a group.

Why this is important:
There is no need to create the order in FunnelCore. The main need is simply to assign a tag to a user (for example, “buyer-product-x”) so they can automatically stop receiving the “buy now” sequence.

In many countries there is no Stripe or any way to sell in USD with a credit card, so users rely on external platforms like Hotmart as their checkout.

Without webhook reception, the process requires complex middleware solutions (Zapier/Make + API calls), which creates friction and makes FunnelCore harder to use in these markets.

Adding webhook reception would allow users to seamlessly mark a lead as buyer when a purchase happens outside of FunnelCore, improving the automation flow and making the platform much more flexible globally.