v1 bug: account detection may drift between auth.json and runtime state

[Nirandre]

Background

The manager currently determines the active account by combining multiple local signals, including the shared home auth.json and the desktop runtime state.

During earlier testing, the displayed active account could temporarily differ from the account currently shown inside Codex Desktop when runtime state and auth.json were out of sync.

Goal

Make active account detection stable, explicit, and predictable.

The manager should:

• clearly define which source of truth has priority
• detect conflicts between auth.json and runtime state
• show the correct active account consistently after account switches and manual desktop logins

Expected behavior

• If desktop runtime state is authoritative, the manager should prefer it consistently.
• If auth.json and runtime state disagree, the UI should surface a clear warning state.
• After a completed account switch, the manager should resolve to the target account without drift.

Notes

This is a v1 stabilization issue, not a v2 feature request.