support MCP elicitations (#6947)

No support for request schema yet, but we'll at least show the message
and allow accept/decline.

<img width="823" height="551" alt="Screenshot 2025-11-21 at 2 44 05 PM"
src="https://github.com/user-attachments/assets/6fbb892d-ca12-4765-921e-9ac4b217534d"
/>

codex-rs/core/src/rollout/policy.rs

@@ -64,6 +64,7 @@ pub(crate) fn should_persist_event_msg(ev: &EventMsg) -> bool {
         | EventMsg::ExecCommandOutputDelta(_)
         | EventMsg::ExecCommandEnd(_)
         | EventMsg::ExecApprovalRequest(_)
+        | EventMsg::ElicitationRequest(_)
         | EventMsg::ApplyPatchApprovalRequest(_)
         | EventMsg::BackgroundEvent(_)
         | EventMsg::StreamError(_)