Cannot Select Text in the Prompt Box.

### Describe the bug

Tested on: Copilot `v1.0.54` on Windows Terminal `1.24.11321.0`

I cannot select text in the prompt box to make any changes.
This functionality is so trivial I consider this as a bug, rather than a feature request.
This is particularly annoying when I paste some text into the prompt box.

How to reproduce:
1. Paste this sentence to the prompt box: `What are some cool C# 14 new features?`
2. Use mouse or keyboard (Ctrl + Shift) to select `some cool` and delete it. This won't work.
3. Paste the same sentence to Windows Terminal PowerShell. Try deleting `some cool` phrase using the same method as step 2. It works fine.

### Affected version

v1.0.54

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

Reproduce the problem in the prompt box using the reported Windows Terminal and PowerShell setup, following the paste-and-select steps in the issue. Trace the prompt input handling from that entry point and verify that mouse and keyboard selection can delete the selected text without disrupting normal prompt editing.

Written by the indexing model from the issue text.