Stale worker entries in ~/.claude/daemon/roster.json survive process death, show as "Login required" ghosts

Description

Updating Claude Code while long-running background tasks are active can leave stale worker entries in ~/.claude/daemon/roster.json. The daemon continues to believe these workers exist even after the underlying processes are gone.

Observed behaviour

• Sessions remain visible in the UI as "Login required", even though no Claude processes exist (pgrep -af claude returns nothing).
• The daemon's roster still lists workers.* entries for the dead processes.
• Removing the stale workers.* entries from roster.json resolves the issue immediately.

Reproduction

1. Start a long-running background task in Claude Code.
2. Update Claude Code (e.g. via version bump) while that task is still active.
3. Check ~/.claude/daemon/roster.json — stale worker entries remain for processes that no longer exist.
4. Observe "Login required" ghost sessions in the UI.

Suggested fixes

• Automatically prune workers whose PIDs no longer exist.
• Validate procStart against the current process to detect PID reuse.
• Provide a /doctor --repair-daemon command to clean stale roster entries without manual file editing.

Workaround

Manually remove the stale workers.* entries from ~/.claude/daemon/roster.json. Recovery takes about a minute once you know where to look.