Codex App: Archived threads should keep latest renamed title

Summary

In Codex App, archived threads should display and retain the latest thread title that was explicitly set while the thread was active (after rename).

Problem

Currently, archived threads do not reliably reflect the latest renamed title. This makes it hard to find the right archived thread and forces users to restore/open threads just to identify or update them.

Expected behavior

• If a thread is renamed while active, that latest title is persisted.
• After archiving, the archived entry shows that same latest title.
• Unarchive/re-archive should not reset or lose the latest explicit title.

Actual behavior

Archived thread entries can show an outdated/non-final name, so users cannot reliably identify previously structured threads in archive.

Why this matters

Many users rename and structure threads before archiving. Losing that name continuity in archive significantly reduces discoverability and creates unnecessary restore/edit cycles.

Suggested acceptance criteria

1. Rename active thread -> archive -> archived list shows renamed title.
2. Unarchive -> rename again -> archive -> archived list shows newest renamed title.
3. Title consistency remains across app restart.

Related

Potentially related to cross-surface naming consistency: #13470