Create Monthly Switch Portal

Switch an annual Team subscription to monthly.

Paid annual subscribers get Stripe's confirmation UI: the server does not mutate the subscription; Stripe shows the exact unused-time credit and applies the update only after the customer explicitly confirms it.

TRIALING annual subscribers (deal-link 30-day opt-out window) are switched directly with trial_end="now": monthly has no trial by policy, so the switch ends the window and charges the first $499 immediately. The console button states the charge; error_if_incomplete keeps the subscription unchanged if the card declines.