Session status indicator in sidebar (running vs. completed)

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

When running 10+ concurrent sessions, the sidebar shows all sessions
with identical appearance. There is no visual indicator of whether a
session is still running or has already completed. To find a finished
session, I have to click into each one individually — which defeats
the purpose of running parallel sessions.

Proposed Solution

Add a small status dot to each session row in the sidebar:

• Pulsing/animated dot → session is actively running
• Green dot → session completed successfully
• Red dot → session ended with an error

This UI pattern already exists in Claude Code: the "Preview" button
shows a green dot when the server is running. The same concept should
be applied to session list items.

Alternative Solutions

No workaround exists. I manually click through every session to check
its status one by one. There is no filter or indicator to show only
completed sessions.

Priority

Critical - Blocking my work

Feature Category

Interactive mode (TUI)

Use Case Example

1. I launch 10 parallel sessions to work on different parts of a project
2. Each session runs for several minutes
3. I need to know when a session finishes to review its output
4. Without status indicators: I click all 10 sessions one by one
5. With status indicators: I see at a glance which are done and jump

directly to them

Additional Context

_No response_