New SubscriptionContractCalculation API for subscription management

A new SubscriptionContractCalculation API is now available to manage subscriptions. This new API runs subscription contract edits through Shopify’s checkout engine, enabling new capabilities: Shopify Functions, including cart transforms and delivery customizations are supported during contract calculations Contract edits align with what the subscriber sees during billing Get a preview of the full calculated contract (totals, delivery options, and warnings) before persisting any changes Developers using the SubscriptionDraft API should migrate to SubscriptionContractCalculation API. The Subscri