PgDn key in Amazon Q chat bot breaks UI visually

## Problem
pressing PgDn in the chat window, at least when the window is docked right full height, breaks the UI where the chat input is now middle of the pane, half hidden to the left. and the responses start hidden.

Restart of VSCode required to reset.

## Steps to reproduce the issue
Dock right side (don't know if that's required, but that's how I work)
in chat input box, press PgDn (instead of the End I was aiming to press)

I've seen this for the last two weeks, finally figured out the cause.

## Expected behavior
Not break the UI.

## System details (run `AWS: About` and/or `Amazon Q: About`)

Latest (auto updated 3 days ago), windows 11, 5k monitor.

Start by reproducing the issue in the Amazon Q chat input with the panel docked on the right at full height on Windows 11, comparing PgDn with End. Done means pressing PgDn no longer moves or hides the chat input and responses, and the UI does not require a VS Code restart to recover.

Written by the indexing model from the issue text.