audit: module-by-module code audit fixes and test coverage

Lands the code-audit branches for aacs, css, keys, labels, udf, ifo and
dvd, bdnav/mpls/clpi, disc/bluray, extract, io, scsi, the mkv, mp4,
network and mpg muxers, the audio and video codecs, and CI. Fixes
include MKB and FMTS validation, UDF bounds, IFO fallback to the BUP,
DTS Express framing, MPEG-2 field pairing and mpg re-basing; the rest
pins existing behaviour with tests.

tests/macos_platform_tests.rs

@@ -1,7 +1,7 @@
 //! macOS platform-integration tests that do NOT require an optical drive.
 //!
-//! These exercise the Mac-only code paths under `platform/fs_type/macos.rs`,
-//! `io/platform_macos.rs`, and `io/writeback_file` end-to-end against the real
+//! These exercise the Mac-only code paths under `io/platform_macos.rs`
+//! and `io/writeback_file` end-to-end against the real
 //! kernel. They run under `cargo test` without `--ignored`, so CI on macOS
 //! (and the local `cargo test` a developer would run before pushing) covers
 //! them automatically.
@@ -76,6 +76,13 @@ fn writeback_file_create_with_size_hint_preallocates() {
         4096,
         "reported length should equal bytes written"
     );
+    // F_PREALLOCATE reserves the hint's extents (st_blocks is in 512-byte units); the
+    // call is best-effort in production, so only this check observes it.
+    let allocated = std::os::unix::fs::MetadataExt::blocks(&meta) * 512;
+    assert!(
+        allocated >= hint,
+        "hint not preallocated: {allocated} bytes"
+    );
 }
 
 #[test]