- Ensure disk metrics from /nodes endpoint are preserved when GetNodeStatus fails
- Add better fallback logic to prevent showing 0% or '-' for disk usage
- Improve logging to distinguish between rootfs and /nodes endpoint metrics
- Handle cases where neither rootfs nor valid node disk data is available
This fixes the regression introduced in v4.12.1 where disk stats would show as
'-' when GetNodeStatus failed due to network issues or rate limiting
