curl -X POST "https://olive-gateway-a6ba.onrender.com/api/v1/admin/refresh" \
  -H "Content-Type: application/json" \
  -d '{
    "refresh_token": "rt_abc123xyz..."
  }'

{
  "success": true,
  "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "refresh_token": "new_refresh_token_string",
  "expires_at": 1704110400,
  "refresh_expires_at": 1704714400,
  "user": {
    "id": "123",
    "email": "admin@olive.sl",
    "first_name": "Admin",
    "last_name": "User",
    "role": "system_admin",
    "status": "active"
  }
}