enzstd creates Zstandard compressed stream of frames, where each frame
holds exactly single WARC record. It also explicitly adds checksum.
Utility takes records from stdin, where each record has 64-bit
big-endian length prefix.

unzstd decompresses Zstandard frames stream from stdin to stdout. If
stream starts with the dictionary (either compressed, or uncompressed)
it is loaded first. If 3rd file descriptor is opened, then each frame's
offset (its size) with decompressed data size is printed in
tab-separated format. If the stream contains dictionary, then first
frame's data size equals to zero.