[BUG] Sidebar with chat history completely disappears on smaller window sizes — no toggle button to restore it

Description

When the Claude Desktop window is resized to a smaller width, the left sidebar (containing chat history) completely disappears with no hamburger menu icon or toggle button to bring it back. The only way to access chat history is to maximize/enlarge the window again.

This is a serious UX issue — users may think their conversation history was deleted, especially after troubleshooting other issues like black screen/cache clearing.

Steps to Reproduce

1. Open Claude Desktop on Windows
2. Resize the window to a smaller width (not maximized)
3. Observe: the sidebar with chat history is completely gone
4. There is no button/icon to toggle the sidebar back

Expected Behavior

A hamburger menu icon or toggle button should appear when the sidebar is hidden due to window size, allowing users to access their chat history at any window size.

Environment

• Claude Desktop version: 1.1.4010.0 (MSIX)
• OS: Windows 11
• Installation: Microsoft Store (MSIX package)