Update an existing application's attributes.

You can update:

• app_name - The application name
• app_webhooks - Webhook configurations
• app_urls - Application URLs (return, domain)
• payment_policy - Which payment rail the application uses, INST or SEPA
• allow_retry_on_failure - Whether the PSU can retry after a failed payment

🔒 This endpoint requires an OAC (Organisation Access Credentials — ⚠️ Beta) access token with the applications:write scope.