billing.ts (startCheckout, openBillingPortal): replace raw res.text()
in thrown Error with a safe status-only message. The response body from
/cp/billing/* routes can contain Stripe API error detail (invalid key,
card decline message, raw Stripe envelope) that should not reach clients.
orgs/page.tsx (createOrg): same fix — raw body → safe message.
Full body is logged server-side for debugging.
Closes: #91 (CWE-209 — Stripe key echoed in error)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>