Model/Thinking Settings Dropdown Hidden in Copilot Chat

- Copilot Chat Extension Version:
- VS Code Version:1.136
- OS Version: Windows 11 25H2
- Feature (e.g. agent/edit/ask mode): sidebar compact UI
- Selected model : Nvidia nim models (using [BaUka0/nvidia-nim-provider](https://github.com/BaUka0/nvidia-nim-provider) extension)
- Logs:

Steps to Reproduce:

1. Install and enable the nvidia‑nim‑provider extension.

2. Open Copilot Chat in VS Code.

3. Observe that the model and thinking settings dropdowns are clipped/hidden

Expected Behavior:

- Dropdowns should remain visible and accessible regardless of panel width.

- The UI should adapt responsively so that controls are usable even in narrower layouts.

Actual Behavior:

- The dropdowns are hidden or clipped, making them inaccessible without resizing.

Added screen shots for reference