auto cleanup of idle tasks

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

In a longer session with many sub agents spawned, there are several pages of tasks that I need to browse through to see my actual current tasks.

### Proposed solution

Allow me to either multi-select tasks that I want to kill, or rather give me an option to auto-kill tasks that have been idle for more than X amount of minutes. The manual approach to killing a task and then deleting it from the list is too much after a very long session.

### Example prompts or workflows

_No response_

### Additional context

_No response_