[FEATURE] Desktop app has no tree view for CLI sessions

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

The session list UI is a flat dump with no hierarchy or structure, making it difficult to navigate across multiple sessions or projects.

Proposed Solution

Add a tree view for sessions (grouped by project/directory) to replace or supplement the current flat list. OpenAI Codex desktop app presents them in a navigable tree view, making it easy to see what's being worked on, and how many sessions per project.

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

Other

Use Case Example

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Additional Context

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