Add recognized_revenue_type to plan response object in core API (list/get). It should also be included in the "plans" subelement on the product object.

🔍 Problem Statement

The Core API plan response object does not include the recognized_revenue_type field. Developers must make separate calls or check the dashboard to determine how revenue is recognized for a plan, which adds integration complexity.

💡 User Story

As a developer, I want recognized_revenue_type included in the plan API response, so that I can determine revenue recognition method in a single call.

🎯 Definition of Done (DoD)

A feature is done when:

✔️ Given a plan API request (list or get), when the response is returned, then it includes the recognized_revenue_type field.