Agent sidebar keeps loading or doesn't show create chat + icon to start interaction. Works fine inline but doesn't work in sidebar

## Problem

## Steps to reproduce the issue

## Expected behavior

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

- OS:
- Visual Studio Code version:
- AWS Toolkit version:
- Amazon Q version:

Start by reproducing the sidebar loading and missing create-chat icon behavior described in the title, comparing it with the working inline interaction. Gather the requested OS, Visual Studio Code version, AWS Toolkit version, and Amazon Q version using `AWS: About` and/or `Amazon Q: About`; the issue does not identify files, tests, or a clear completion condition.

Written by the indexing model from the issue text.