onResendEmailSuppressed emits email.suppressed when Resend declines to send
a message, commonly because recipient or account policy says it should not be
attempted.
automations/handle-resend-suppression.automation.ts
account defaults to the project binding. Returns
{ type: "email.suppressed"; createdAt; data }, with provider-native reason,
recipient, and email fields when Resend supplies them. A suppressed event is
distinct from a failed attempt or recipient-server bounce.