Restore opt-in passive context meter in Codex desktop app

## Summary

Please restore an opt-in passive context meter in the Codex desktop app.

/status is useful, but it is not equivalent to ambient context awareness during long-running threads. A small, clearly labeled indicator like Context 68% used or Context 32% remaining, visually separated from quota/rate limits, helps users decide when to compact, fork, or start a fresh thread without interrupting workflow.

Why this matters

The previous passive indicator was especially useful for long Codex app conversations where context pressure directly affects output quality and planning. For power users, passive context visibility is not cosmetic; it informs when a thread is getting close to compaction territory and when a fresh thread would be healthier.

If confusion with rate limits was the concern, clearer labeling and an advanced-setting toggle would solve that without removing the signal for users who rely on it.

Suggested behavior

• Add an advanced/optional setting for a passive per-thread context meter.
• Label it explicitly as conversation context, not quota or rate-limit usage.
• Keep it visually separate from 5-hour and weekly usage limits.
• Support either Context N% used or Context N% remaining; the important part is that it is passive and visible without running /status.

Related feedback

I also submitted this through the Codex feedback form. Feedback ID: 019e48ff-3e50-7750-87c8-4d29a4fd0ab8.