Finalize WhatsApp Business onboarding (iframe-initiated)
Finalize WhatsApp Business onboarding (iframe-initiated)
Called from the connect-page iframe with the page token + X-Account-Id. Atomically reserves the token, exchanges the OAuth code for an access token, subscribes the app to the WABA, persists the WABA-side fields, then best-effort registers the phone number if provided. Phone registration is non-fatal: on failure the workspace stays WABA-connected and the response carries phone_status="registration_failed".

