Create Cal.com managed users via the Platform API and manage their OAuth tokens

Documented steps

1. POST https://api.cal.com/v2/oauth-clients/{clientId}/users with header x-cal-secret-key: <oauth client secret>, Content-Type: application/json (Platform plan required; clientId is a PATH param, not a header)
2. Body: {"email": "..." (required), "name": "..." (required), optional timeZone, timeFormat (12|24), weekStart, locale}
3. Response 201: {status: 'success', data: {user, accessToken, refreshToken}} — store both tokens server-side; access tokens expire in 60 minutes, refresh tokens last ~1 year
4. Refresh: POST https://api.cal.com/v2/auth/oauth2/token style refresh with the refresh token and client credentials; if the refresh token itself is lost/expired, use the force-refresh endpoint POST /v2/oauth-clients/{clientId}/users/{userId}/force-refresh with x-cal-secret-key
5. Use the managed user's accessToken as Authorization: Bearer <token> on v2 endpoints (bookings, schedules, event types) to act as that user
6. Docs: https://cal.com/docs/api-reference/v2/platform-managed-users/create-a-managed-user and https://cal.com/docs/platform/quickstart