Add tags and/or folders for organizing sessions in VSCode sidebar

After a few weeks of using CC in VSCode I've got nearly 30 sessions in the sidebar for the same workspace, with no way to organize them. They're just a flat list by date. I've been hacking around it by prefixing session titles like [debug] login issue or [NHA] feature work, but that doesn't really scale.

Would be great to have some way to group sessions — folders, tags, or both.

Folders are familiar: drag and drop a session into one, right-click to rename, etc. Tags are more flexible since one session can belong to several at once (a debugging session that's also about auth, say). Both would be useful for different reasons; tags for filtering, folders for explicit organization. Claude.ai's web UI does something similar with Projects.

Some UI ideas:

• Right-click → Move to folder / Add tag
• Drag-and-drop between folders
• Filter bar at the top to filter by tag
• Tag chips next to the session title
• Persist in something like ~/.claude/projects/<cwd>/.session-groups.json so it survives restarts

Probably worth looking at alongside #43666 (session list improvements) and #26211 (live status indicators) since they all touch the same area.

Extension version 2.1.138.