Package archive streams a directory through tar+zstd (and back).
Compression level is fixed at zstd level 3 — same as the existing shell
(`zstd -T0 -3`). The encoder is wrapped around an io.Writer (typically an
S3 multipart Uploader's PipeWriter), so the whole pipeline stays
streaming end-to-end with no on-disk tempfile.
EncodeDir walks root in sorted relative-path order and writes a
tar.zst stream into w. Symlinks are preserved (stored as tar typelink),
devices/sockets/fifos are skipped.
Package archive streams a directory through tar+zstd (and back).
Compression level is fixed at zstd level 3 — same as the existing shell (`zstd -T0 -3`). The encoder is wrapped around an io.Writer (typically an S3 multipart Uploader's PipeWriter), so the whole pipeline stays streaming end-to-end with no on-disk tempfile.