Render plan headings without visible Markdown markers

What variant of Codex are you using?

codex-cli 0.144.1.

What feature would you like to see?

When Codex CLI presents a plan, headings written with Markdown ATX syntax are displayed with their literal markers, for example:

# Plan
## Implementation

Please render plan headings without showing the leading # or ## markers. The heading hierarchy can still be communicated through the existing terminal styling, indentation, spacing, or emphasis.

For example, the displayed output could be:

Plan
Implementation

This should only affect presentation in the CLI/TUI; it should not require rewriting the underlying plan content or changing Markdown.

Additional information

Visible Markdown syntax makes plans feel noisier and less polished in the terminal. Since plan output is a structured Codex UI surface, its renderer can present headings cleanly rather than exposing source-formatting characters.

<img width="656" height="676" alt="Image" src="https://github.com/user-attachments/assets/f45c95dc-6261-465d-a3e5-270cd1be3b84" />