hugetop: print human readable sizes by default

Original size format ```shell $ cargo run -q hugetop hugetop - Thu Apr 30 16:34:42 2026 node(s): 2048kB - 0/0, 1048576kB - 0/0 ``` Consistent with the hugetop command of `procps-ng`, change the default size to a format suitable for human reading ```shell $ cargo run -q hugetop hugetop - Thu Apr 30 16:34:42 2026 node(s): 2.0Mi - 0/0, 1.0Gi - 0/0 ```