Allow Scheduled Renewal Phase to Start Early

🔍 Problem Statement

For shipment-based subscriptions, a subscription can reach 0 shipments remaining while there is still time left in the current subscription period. The renewal is scheduled to begin once the current period ends, but there is currently no way to activate the renewal early. This prevents the subscriber from being included in an upcoming fulfillment when the publisher needs to start the next shipment cycle before the current period ends.

💡 User Story

As a publisher managing shipment-based subscriptions, I want to manually activate the next scheduled renewal before the current subscription period ends, so that subscribers who have exhausted their shipments can be included in an upcoming fulfillment without waiting for the current period to expire.

🎯 Definition of Done (DoD)

✔ Authorized users can manually activate the next scheduled renewal before the current subscription period ends.
✔ The subscription moves to the renewal phase and receives the appropriate shipment allocation when activated.
✔ The subscriber becomes eligible for the next fulfillment/shipment list.
✔ Scheduled renewals continue to activate automatically at the end of the current period when no early activation is performed.