v0.2.8

• Framed containers (framed feature). mzstd::framing ports
  mbrotli's structured framing API one to one — FramedCompressor with
  borrowed one-shot input, native and owned sessions, resource guards,
  FramedWriter/ResourceWriter and FramedEncoderReader;
  FramedDecompressor with owned, appended and sliced one-shot output,
  event sessions, FramedReader and the random-access FramedSeekReader;
  resources, metadata (resource, footer, global, repeated), padding,
  hidden resources, explicit dictionary references, a central directory and
  a footer. In place of RFC 9841's Brotli wire format the container is made
  only of Zstandard frames: visible resource chunks are regular frames,
  byte-identical to ZSTD_compress2 of each chunk, so zstd -d prints the
  visible resources; headers, metadata, hidden resources and the directory
  live in skippable frames; and the container ends with a seek table in
  zstd's contrib/seekable_format layout. Tests check every container
  against ZSTD_decompress and the contrib seekable decoder, which
  zstd-ffi now builds as an oracle (along with the contrib seekable
  compressor, the benchmarks' baseline). The fuzz package's opt-in
  experimental feature is replaced by framed, which gates the
  framed_encode, framed_decode and framed_roundtrip targets. The
  format is specified in architecture/framing.md; the API may change in
  patch releases while the feature is opt-in.

• Clarified ParallelTaskQueue documentation. Stopped executors can
  leave wait, the blocking reader and writer and the writer's finishing
  waiting indefinitely; dropping queue handles or tasks reports closure or
  abandonment when the session observes it. Tasks executors already hold
  must still be run or dropped.

• Parallel batches over random-access sources.
  ParallelCompressor::prepare_source plans a batch over a
  RandomAccessSource instead of a borrowed slice, as mbrotli's does, and
  returns an OwnedParallelBatch whose tasks are 'static, so they run on
  detached threads or any executor. Each task reads its segments and their
  overlap into one reused buffer; the frame is byte-identical to
  prepare_slice over the same bytes. ArcBytesSource (shared Arc<[u8]>),
  SeekSource (any Read + Seek + Send reader behind a mutex) and
  FileSource (positional reads of a regular file) implement the trait,
  and SourceIdentity lets a source carry a version token. finish checks
  that the source's length and identity are unchanged
  (ParallelEncodeError::SourceChanged) and, for a frame with a checksum,
  reads the source once more to hash it. Source failures are
  SourceMetadata and SourceRead { segment }, carrying the io::Error
  in a SourceIoError so the error stays Clone + Eq.