## Summary
- Add a "Cancel subscription" button to the billing card for Pro and Scale users, alongside the existing "Manage billing" portal link.
- Cancellation is scheduled end-of-cycle via `autumn.updateSubscription({ planId, cancelAction: "cancel_end_of_cycle" })`, so users keep paid features until period end.
- Confirmation dialog surfaces remaining days from `useTokenUsage` and the correct plan name (Pro/Scale).
- Enterprise users do not see the cancel button — contract-based, portal/sales only.
Previously, the only path off a paid plan was Autumn's external customer portal, which contradicted the in-app "cancel anytime from the Billing tab" copy in the support FAQ.
