Fix effort and provider handling in thread turn start

- Only include `effort` in start command when a value is selected
- Persist effort selection via composer draft state and hide picker when unavailable
- Add optional `provider` to `ClientThreadTurnStartCommand`
- Simplify thread model fallback selection in `ChatView`
feff86638eJulius Marminge committed on 3/6/2026, 7:00:41 AM· committed by Julius Marmingeparentad28eaa
2 files changedLine totals unavailable