Tracking high‑risk unwrap() removals

[naoNao89]

P0 (fix first)

• install — status.code().unwrap() after strip (feat(install): improve robustness, error handling, and internationalization #9451)

• sync — File::open(path).unwrap() in do_syncfs / `do_fdatasync (sync: Reset O_NONBLOCK flag after file validation to match GNU behavior #9437)

• timeout — unwrap() on exit status / signals / signal lookups (timeout: Improve error handling with explicit expect messages #9435)

• stdbuf — status.signal().unwrap() when child is killed (Remove unsafe unwrap() calls in stdbuf error handling #9429)

• chroot — canonicalize(...).unwrap() for newroot / --skip-chdir

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P1 (next)

• nice — raw_os_error().unwrap(), CString::new(...).unwrap()

• nohup — CString::new(...).unwrap() for command

• utmpx — CString::new(path.as_bytes()).unwrap()

• split — c.try_into().unwrap() for sizes/counts

Related: #9341

[oech3]

#9348 (comment) #8474