sync: non-ErrNotExist stat errors silently treated as "copy" in Tar.Sync()

[ishwar170695]

Location: internal/sync/tar.go, Sync() function

Problem:
The current logic buckets paths into copy vs delete:

if _, err := os.Stat(p.HostPath); err != nil && errors.Is(err, fs.ErrNotExist) {
    pathsToDelete = append(pathsToDelete, p.ContainerPath)
} else {
    pathsToCopy = append(pathsToCopy, *p)
}

Non-NotExist errors (e.g. EACCES, EIO) are silently ignored and the path is
treated as copyable. This means permission or IO errors don't stop the sync ,
the operation may fail later in a less obvious place with the original cause lost.

Expected behavior:

    if err == nil {
        pathsToCopy = append(pathsToCopy, *p)
    } else if errors.Is(err, fs.ErrNotExist) {
        pathsToDelete = append(pathsToDelete, p.ContainerPath)
    } else {
        return fmt.Errorf("stat %q: %w", p.HostPath, err)
    }