Issues an OAuth2 access token using the client-credentials flow. Use the client_id and client_secret generated in ROLLER Venue Manager.

Tokens are valid for up to 24 hours and are cached server-side — repeated calls may return the same token with a decreasing expires_in. Cache the token in your application and refresh shortly before expiry.

Rate limit: 60 requests per minute per IP (5-minute cooldown when exceeded).