Non-root users can change modes for root-owned files and directories

For some reason, non-root users can change modes on files and directories owned by root (e.g. `/root`).
# Steps to reproduce
1. Open iSH
2. Check `ls -lahd /root`
3. Add a new user `nonroot`.
4. Do `su nonroot -c "chmod o+rx /root"`
5. Check `ls -lahd /root` again.
# Full test
```
ls -lahd /root
adduser -S -D -H nonroot
su nonroot -c "chmod o+rx /root"
ls -lahd /root
deluser nonroot
````

Start by running the full test in iSH and tracing how chmod handles ownership and permission checks for /root. Done means a non-root user cannot change modes on root-owned files or directories, while the listed commands continue to behave correctly for permitted users.

Written by the indexing model from the issue text.