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/writeback_file/macos.rs

@@ -1,10 +1,12 @@
 //! macOS platform impl for [`super::WritebackFile`].
 //!
 //! - `preallocate`: `fcntl(F_PREALLOCATE)` — macOS's fallocate-equiv.
-//!   Reserves a contiguous extent when possible, falling back to a
-//!   non-contiguous reservation if the FS can't satisfy it. Reported
-//!   file size is unchanged (`F_ALLOCATEALL` is not set, so allocation
-//!   is "best effort up to length"; growth happens via writes).
+//!   First attempt requests `F_ALLOCATECONTIG | F_ALLOCATEALL` (prefer a
+//!   contiguous run but accept scattered extents to satisfy the full
+//!   length), falling back to `F_ALLOCATEALL` alone on failure.
+//!   `F_PREALLOCATE` never advances EOF regardless of the flags — only
+//!   `ftruncate`/writes grow the file — so the reported file size is
+//!   unchanged; `F_ALLOCATEALL` governs the contiguity fallback, not size.
 //! - `durable_sync`: `fcntl(F_FULLFSYNC)` wrapped in
 //!   [`crate::io::bounded::bounded_syscall`] with a 60 s deadline.
 //!   F_FULLFSYNC is HFS+/APFS's true-fsync (flushes the disk's own
@@ -25,11 +27,14 @@ use crate::io::platform_macos::{
 const F_FULLFSYNC: libc::c_int = 51;
 
 pub(super) fn preallocate(file: &File, size_bytes: u64) {
+    // Clamp to the signed `off_t` range; an unchecked `as off_t` cast
+    // would wrap a >= 2^63 size to a negative length.
+    let len = i64::try_from(size_bytes).unwrap_or(i64::MAX) as libc::off_t;
     let mut fst = Fstore {
         fst_flags: F_ALLOCATECONTIG | F_ALLOCATEALL,
         fst_posmode: F_PEOFPOSMODE,
         fst_offset: 0,
-        fst_length: size_bytes as libc::off_t,
+        fst_length: len,
         fst_bytesalloc: 0,
     };
     // First attempt: contiguous.