ACP: add `reject_always` permission option

Feature request for product/service

Cursor CLI

Describe the request

Cursor’s session/request_permission offers allow_once, allow_always, and reject_once — but not reject_always. The ACP spec defines all four PermissionOptionKind values.

Without reject_always, users have to manually reject every single invocation of a tool they don’t want. Gets tedious fast in long sessions.

Operating System (if it applies)

MacOS