Chat pane minimum width is fixed and cannot be resized

Issue
The chat window pane (right side) has a fixed minimum width (~70% of the window) and cannot be resized narrower, even when dragging the divider all the way left.

Expected behavior
Previously the chat pane width was freely resizable. Users should be able to adjust it to any width.

Steps to reproduce

1. Open Claude Code desktop app
2. Drag the divider between sidebar and chat pane to the left
3. The divider stops at a certain width and won't go further

Environment

• Platform: Windows 11
• Date: 2026-06-13
• This appears to be a recent regression — worked in previous versions

Additional context
The sidebar itself resizes fine, only the chat pane minimum is locked.