"Show Paste Options" not shown in Copilot Chat

Describe the bug
With VSCodeVim enabled, pasting code into the Copilot Chat doesn't trigger the "Show Paste Options" experience.

To Reproduce

1. Enable VSCodeVim.
2. Open a source file. (I've tried Python, XML.)
3. Copy a code snippet (3-5 lines) into the clipboard. It doesn't seem to matter how (mouse-select, then Ctrl-C / Cmd-C; or yank using "*y).
4. Open Copilot chat ("Chat: Focus on Chat View").
5. Paste the snippet into the chat.
   • Expected behavior: A blue floating button appears at the bottom of the pasted text. It offers paste options (paste as inline text or as an attachment). See the screenshot below.
   • Actual behavior: The "Show paste options" button does not appear.
6. Disable VSCodeVim.
7. Restart VSCode.
8. Copy text again. (Don't use what's already in the clipboard.)
9. Paste.
10. This time the blue icon appears.

Screenshots

Environment (please complete the following information):

• Extension (VsCodeVim) version: 1.29.0
• VSCode version: 1.99.3
• OS: Windows 11

Start by reproducing the interaction between VSCodeVim 1.29.0, VS Code 1.99.3, and Copilot Chat using the steps in the issue on Windows 11. Trace the paste flow and determine why disabling VSCodeVim restores the button; done means the "Show paste options" button appears when pasting code with VSCodeVim enabled.