Credit pools for subscriptions added

It is now possible to work with multiple credit pools within a single subscription. This allows a subscription to contain different types of credits, each with its own rules and settings regarding which lessons or services can be booked with them.

For example, a customer can have unlimited free training within the same subscription, but also receive group class credits once a week. Multiple packages or credit types can also be combined, allowing coaches and studios to create more flexible subscriptions that better align with their offerings.

Credit pools make it easier to clearly manage various lesson formats, services, and access rights within a single subscription.