0.31.0: hardening and correctness pass across mux, codec, AACS/CSS, UDF/MPLS/CLPI, recovery, drive/SCSI, labels, and I/O

Library-wide review-and-fix pass: tightened AACS keydb/handshake/variant
handling and trailing-partial-unit policy, corrected MPLS mark offset and
added UDF allocation bounds, hardened the mux/codec framing and M2TS paths,
guarded SCSI READ CAPACITY short transfers and unified error mapping, added
overflow guards on untrusted disc input, and made prefetch shutdown
deterministic. Release profile now builds with thin LTO + single codegen unit.

src/io/mod.rs

@@ -18,15 +18,16 @@
 //! consumed window so an 85 GB streaming ISO read doesn't fill the
 //! page cache and starve the concurrent MKV write.
 //!
-//! `Pipeline` + `Sink` (0.18) is the generic producer/consumer primitive
+//! `Pipeline` + `Sink` is the generic producer/consumer primitive
 //! used by sweep, patch, and mux to overlap reads with writes via a
 //! bounded channel + dedicated consumer thread.
 //!
-//! `byte_channel` is a byte-sized producer/consumer channel for the
-//! mux pipeline, sized to absorb worst-case input read stalls.
+//! `byte_prefetcher` is the read-ahead producer feeding the mux
+//! pipeline for `io::Read`-backed sources: a worker thread fills a
+//! recycled pool of buffers and ships them through a channel, exposing
+//! `BytePrefetcher` / `PrefetchShell`.
 
 pub(crate) mod bounded;
-pub mod byte_channel;
 pub mod byte_prefetcher;
 pub mod file_sector_source;
 pub mod sink;
@@ -40,8 +41,6 @@ pub mod pipeline;
 
 pub(crate) use writeback_file::WritebackFile;
 
-// Re-exports for the 0.18 redesign. Sweep, patch, and mux are all
-// wired up (disc/sweep.rs, disc/patch.rs, autorip's ripper/mux.rs).
 pub use pipeline::{
     DEFAULT_PIPELINE_DEPTH, Flow, Pipeline, READ_PIPELINE_DEPTH, Sink, WRITE_PIPELINE_DEPTH,
     WRITE_THROUGH_DEPTH,