IAV-1400/fix(whatsapp): use exchanged long-lived token when building n8n credential
Fixed a bug where the WhatsApp exchanged long-lived token was not propagated to the n8n credential.
The payload was built from the original credential map instead of the updated one containing the new token,
causing all WhatsApp API calls to fail with a 401 once the short-lived token expired.
Fix: pass the updated credentials map (post-exchange) to mapToN8nFormat() instead of request.getCredentialData().
Closes IAV-1400