Change model for enqueued prompts

### Describe the feature or problem you'd like to solve

Cannot use /model while agent is running.

The option to enqueue prompts (ctrl + enter) is very useful, however, it is currently not posible to run the /model command while the agent is active. Users wanting to add an enqueued command with a different model will have to wait until the current task is complete.

### Proposed solution

Solution is to enabling /model to specify the model used for subsequent propts while a task is running, sparing users the wait.

### Example prompts or workflows

Advanced model is running task, I want to enqueue command to push using simple model once it is finished.

Advanced model is running task, I want to make simple addition with simpler model at end of task.

### Additional context

_No response_