Public Checkout

Create a Stripe Checkout session without requiring authentication.

Designed for shareable checkout links (/checkout/pro, /checkout/enterprise) where the user pays before creating a Pioneer account.

Rate-limited to 10 requests per IP per minute since the endpoint is unauthenticated and each call creates a Stripe Checkout Session. Captcha verification required in non-local environments.

Args: request: FastAPI request (required by SlowAPI rate limiter). body: Plan, redirect URLs, and optional email.

Returns: Stripe-hosted checkout URL.