The compressibility heuristic compressed a 1 MiB sample of each upload
into a bytes.Buffer only to read its length, growing up to ~1 MiB of
garbage per file. Write the sample through a counting io.Discard-style
writer instead so no output buffer is allocated at all.
Added support for reading and writing zstd-compressed archives in seekable format
using "github.com/klauspost/compress/zstd" and
"github.com/SaveTheRbtz/zstd-seekable-format-go/pkg".
Bumped Go version from 1.24.0 to 1.24.4 due to requirements of
"github.com/SaveTheRbtz/zstd-seekable-format-go/pkg".
Nick Craig-Wood
Alex