Restore a previously deleted domain (undo delete)

Undo a prior <code>DELETE /v1/domain/{id}</code> call. Restores a domain whose <code>status</code> is <code>"deleted"</code> back to <code>"active"</code> and releases the reserved AnnualFlexi slot (if one was created at deletion time).

<strong>Preconditions:</strong> The domain must currently be in <code>status: "deleted"</code>. Calling revoke on an <code>active</code>, <code>inProgress</code>, <code>failed</code>, or <code>expired</code> domain is rejected.

<strong>Semantics — revoke vs. delete:</strong> <code>DELETE /v1/domain/{id}</code> moves an <code>active</code> domain into <code>deleted</code>; <code>POST /v1/domain/{id}/revoke</code> moves a <code>deleted</code> domain back to <code>active</code>. Revoke acts on a single domain — it does not affect sibling domains in the same order.

Use <code>domains[].id</code> from <code>GET /v1/domain</code>.