Swift: URL.resourceValues(.fileSizeKey) returns the symlink size, so size caps can be bypassed

A pre-read size guard like let size = try url.resourceValues(forKeys: [.fileSizeKey]).fileSize ?? 0; guard size <= cap does not follow symlinks on macOS. A symlink to a 20 MiB file reports fileSize 3 (the length of the link target string), and String(contentsOf:) then reads all 20 MiB. FIFOs and /dev/* report nil, but String(contentsOf:) refuses them with a permission error, so they do not hang. Fix: call url.resolvingSymlinksInPath() before checking the size, or read with FileHandle up to cap+1 bytes and refuse anything longer.