Add JAR parser: extract audio/subtitle labels from BD-J menus

Scans BDMV/JAR/*.jar class files for track label patterns:
 eng_MLP_ → TrueHD, eng_ADES_US_ → Descriptive Audio (US)
 dan_PGStream4 → Danish subtitles

Solves the "3x AC-3 English" problem — we identify Descriptive Audio, commentary, compatibility tracks.

Future: set MKV "visual impaired" flag automatically during mux.

Local only — needs more disc samples to validate before publishing.

src/lib.rs

@@ -79,6 +79,7 @@ pub mod udf;
 pub mod mpls;
 pub mod clpi;
 pub mod disc;
+pub mod jar;
 
 pub use error::{Error, Result};
 pub use drive::DriveSession;