[FEATURE] Expose 5-hour session and weekly usage percentages to statusline

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The /status Usage tab shows the 5-hour session usage % and weekly usage %, but this data is not included in the JSONpiped to the statusline command. I want to monitor my quota usage at a glance in the statusline without having to open /status every time. Other CLI tools like Codex already surface usage quota data.

Proposed Solution

Add session_usage_percentage and weekly_usage_percentage (and their reset times) to the statusline JSON input, so custom statusline scripts can display quota info. For example:
"usage": {
"session_used_percentage": 6,
"session_resets_at": "2026-03-18T11:00:00Z",
"weekly_used_percentage": 52,
"weekly_resets_at": "2026-03-20T03:00:00Z"
}

Alternative Solutions

Currently I have to manually open /status and navigate to the Usage tab to check quota. There is no way to access this data programmatically or from the statusline.

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

1. I have a custom statusline script that shows context window %, model, and git branch
2. I want to also see "5hr: 6% | week: 52%" in my statusline
3. The data exists in /status but is not in the JSON piped to the statusline command
4. I have to stop what I'm doing and open /status to check, breaking my flow

Additional Context

Codex CLI already shows this data in its statusline:

<img width="673" height="71" alt="Image" src="https://github.com/user-attachments/assets/344d622f-3fb7-49c9-8f68-acda15f6eab1" />