Core API: Export Products and Plans

🔍 Problem Statement

As a developer, the Core API lacks endpoints to retrieve the full catalogue of products and plans. Plans must be fetched product-by-product and there is no bulk products/plans export, which forces manual CSV downloads and prevents automated ingestion into data warehouses or analytics tools.

💡 User Story

As a developer, I want to retrieve a full list of all products and all plans (across every product) via the Core API in a single paginated call, so that I can build integrations and automate data ingestion without manual exports or product-by-product lookups.

🎯 Definition of Done (DoD)

• ✔ Given a valid API token, when calling the list-all endpoints (e.g. GET /v2/products and GET /v2/plans), then all records are returned with full detail, paginated.
• ✔ The plans endpoint returns every plan across all products in one response (no product-by-product iteration required).
• ✔ This change will impact API — new products and plans list/export endpoints, documented and tested.
• ✔ Limitations: read-only in v1; write operations are out of scope.