Allow queueing `/review` requests while agent performs work

Question

### What variant of Codex are you using?

v0.115.0-alpha.1

### What feature would you like to see?

If the agent is busy performing work, I'd like to walk away after:

* Typing `/review check and confirm changes don't cause regression`
* Hit `tab` to queue the command

Right now I see an error:

```
■ '/review' is disabled while a task is in progress.
```

When I know the task is going to take a very long time to finish (multiple potential tool calls, long-running task), I'd like to queue a rev