[FEATURE] Code tab sidebar: project headers are hard to tell apart from session titles

In the Claude desktop app's Code tab, when the sidebar groups sessions by project, the project headers (folder names) look almost the same as the session titles under them. They use the same font size and nearly the same gray, with no icon or divider between groups. With many projects and sessions open, it's hard to see where one project ends and the next begins.

Any one of these would solve it:

1. Give project headers their own style: a bolder or small-caps label, a folder icon, and more space or a divider line above each group.
2. Let users pick a color or icon for each project and show it on the header.
3. Add a sidebar appearance setting, such as "Emphasize project headers".

The workarounds available today don't solve it:

• Custom sections with emoji names need every new session to be moved into them by hand.
• The plugin/mod API can't change how the sidebar looks.

Environment: Claude desktop app on macOS, Code tab, sidebar grouped by project.