Not asking for approval in plan mode

### Describe the bug

I noticed that after it had just come out of auto-pilot mode, after implementing a previous plan, if I was to go into plan mode again, it seemed that it didn't want to ask me for approval of a plan before implementing the changes.

### Affected version

GitHub Copilot CLI 1.0.22

### Steps to reproduce the behavior

1. In plan mode, write an implementation plan for something.
2. After the plan is presented, press "Implement with Autopilot" or "Continue on Autopilot", whatever the option is.
3. After the plan is implemented in Autopilot, shift tab to go back to plan mode.
4. Ask it a follow-up, expecting a new plan.

### Expected behavior

I would still expect this to output a plan and ask me for approval.

### Additional context

I've only noticed this in this current version and the one immediately previous. It may have been there beforehand; I just hadn't noticed it.

Reproduce the issue in GitHub Copilot CLI 1.0.22 by following the plan-mode and Autopilot transition steps. Start by tracing the transition from Autopilot back to plan mode, then verify that a follow-up produces a plan and requests approval before implementation.

Written by the indexing model from the issue text.