[FEATURE] Drag-to-reorder custom session groups in sidebar

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Claude Desktop for Claude Code supports custom session groups but provides no UI mechanism to reorder them. The underlying data structure exists (customGroupOrder in claude_desktop_config.json), but users cannot control group display order in the sidebar.

When organizing sessions it provide principe first create first in the list.
There's no way to manually arrange groups to match workflow priority.

Proposed Solution

Users should be able to:

• Drag and drop groups in the sidebar to reorder them
• Or right-click a group and select "Move up" / "Move down" options
• Order persists across sessions and app restarts

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

AI:
The Desktop app already stores group order in preferences.epitaxyPrefs.dframe-local-slice.customGroupOrder. The infrastructure exists; only the UI control is missing.

Environment

• Platform: macOS (but applies to all platforms)
• Claude Desktop Version: Latest (v2.x)
• Claude Code Version: Latest (v2.1.170+)

Related issue (looks like): #59640 #60954

<img width="500" height="600" alt="Image" src="https://github.com/user-attachments/assets/f2469a84-2e4f-4878-b983-c52ddab167d2" />