Codex CLI: Add fast mode status to the statusline

What variant of Codex are you using?

CLI

What feature would you like to see?

Add a statusline option that displays the current fast_mode status.

/statusline
``
[x] model-with-reasoning Current model name with reasoning level
[x] fast-mode Current fast mode status (omitted when off)
[x] current-dir Current working directory
[ ] context-remaining Percentage of context window remaining (omitted when unknown)
[ ] context-window-size Total context window size in tokens (omitted when unknown)
[ ] model-name Current model name
[ ] project-root Project root directory (omitted when unavailable)
[ ] git-branch Current Git branch (omitted when unavailable)
[ ] context-used Percentage of context window used (omitted when unknown)

gpt-5.4 medium · fast · ~/project/path

in `config.toml`

status_line = [
"model-with-reasoning",
"fast-mode",
"current-dir",
]

### Additional information

_No response_