Agents window Windows Control Overlay does not change with theme

[rzhao271]

1. Open the Agents app on Windows.
2. If the app is on a dark theme, change to a light theme, otherwise, change to a dark theme.
3. 🐛 The Windows Control Overlay on the top-right does not change with the rest of the theme.

[vs-code-engineering]

Hi @rzhao271. As a member of the team, you can help us triage this issue by referring to https://github.com/microsoft/vscode-copilot/wiki/Copilot-Inbox-Tracker and assigning an owner directly.