Session Auto-Rename does not work anymore

### Describe the bug

The title of the AI session or the terminal in which the Copilot CLI session is ongoing captures the last prompt, instead of capturing an AI-generated title of the session.

See for example:

Also, running /rename with no parameters fails:

### Affected version

GitHub Copilot CLI 1.0.49-1.

### Steps to reproduce the behavior

1. Start copilot CLI by running "copilot".
2. Write a prompt.
3. Hit Enter.
4. The title is just the prompt, instead of some AI generated title

### Expected behavior

The title should be an AI-generated description of the session

### Additional context

I am running copilot on a Window device. Also confirmed that the same behavior exists for other uses in Windows.

Start by reproducing the session auto-renaming behavior and the no-argument /rename failure on Windows using the listed steps. Trace the session title update and /rename handling until you can identify the affected entry points; done means sessions receive an AI-generated title and /rename without parameters no longer fails.

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