fix(permissions): normalize paths for macOS filesystem comparison (#33451)
## Summary
- On macOS, APFS resolves Unicode-equivalent and case-differing paths to
the same inode (e.g. NFC/NFD forms, ligatures, upper/lower case).
- `comparison_path` was a no-op on non-Windows platforms, so permission
checks compared raw bytes that the filesystem considers equivalent.
- On macOS, now applies NFKD normalization and Unicode case folding
before comparison, aligning permission checks with actual filesystem
behavior.