[Feature Request] Add session-level effort override without persisting to default configuration

Question

**Bug Description**
would be nice to be able to switch effort for just a session without changing the default. I'd much rather have a default of xhigh and bump it to max or scale it down in a session without it leaking into every new session

**Environment Info**
- Platform: darwin
- Terminal: iTerm.app
- Version: 2.1.170
- Feedback ID: 269f7a30-d756-42a8-beaa-5dbe957d4657

**Errors**
```json
[]
```