Update Global Error Subscribers

Replaces the list of email addresses subscribed to global sync error notifications for the caller's organization. This is a **full replacement** — the request body becomes the complete subscriber list. To add or remove a single address without affecting others, fetch the current list with [`GET /api/notifications/global-error-subscribers`](../../../api-reference/notifications/get-global-error-subscribers), apply your change, and send the modified list back.