Add plan usage data to status line JSON input

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

Currently, the JSON input sent to the status line command includes context
window usage but not account plan usage information.

Include plan/subscription usage data in the status line JSON input:

• Current usage (tokens or percentage)
• Plan limit
• Reset date/time
• Days/hours until reset

This would allow users to display their plan usage alongside context usage
in custom status lines.

Proposed Solution

Example desired JSON structure:
{
"plan_usage": {
"tokens_used": 1234567,
"tokens_limit": 5000000,
"usage_percentage": 24.69,
"reset_date": "2026-02-01T00:00:00Z",
"days_until_reset": 23
}
}

This would be a valuable addition for users who want to monitor their plan limits directly in the status line!

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_