Strlcpy

How buffer overflow happens in C string copy functions and how to fix it

A high-severity buffer overflow vulnerability was discovered in `bin/nad/ftw.c` where unsafe `strncpy()` calls lacked proper NULL-termination guarantees. The fix replaces the vulnerable pattern with `strlcpy()`, a safer bounded string copy function that automatically handles NULL-termination and prevents buffer overflows in file tree walking operations.