Add Enterprise monthly credit limit to /statusline

What variant of Codex are you using?

CLI

What feature would you like to see?

I’d like /statusline to support showing the Enterprise monthly credit limit, similar to the existing 5h and weekly limit items.

Current behavior:

• /status can show Enterprise monthly credit limit data.
• /statusline can show short limit summaries for other limits.
• There is no dedicated /statusline item for the Enterprise monthly credit limit.

Requested behavior:

• Add a new /statusline item named monthly-limit.
• Display it in the same short style as other limit items, for example:
• monthly 68% left
• Refresh the value as other limit items.

This would make Enterprise monthly usage visible in the footer without having to manually run /status.

Additional information

_No response_