labels: add dbp parser (Magnolia Pictures BD-J framework)

5th BD-J authoring framework recognized. Discriminator: any top-
level .jar in /BDMV/JAR/ that contains com/dbp/ package paths.
Identified during the 2026-05-10 corpus session via string-mining
disc-07's BD-J jar — perm files reference bd-live.magpictures.com
(Magnolia / Magnet Releasing).

Stream labels live as plain ASCII strings inside compiled .class
files in the form

    LTextField,Audio1,English Dolby Atmos,Fontstrip_Composite,...
    HTextField,Subtitle1,English SDH,Fontstrip_Composite,...
    ATextField,Subtitle0,None,Fontstrip_Composite,...

— a quirk of the menu-rendering layer encoding TextField positions
and content as constant strings the Java compiler retained in the
class string pool. The leading single-letter prefix is string-pool
ordering noise; parser anchors on `TextField,`. Subtitle0 is the
disable-subtitles button and is skipped.

The parser:
  - reads each top-level .jar via udf.read_file
  - opens it with the existing zip dependency
  - confirms com/dbp/ presence in the central directory
  - walks .class entries, extracts printable strings, matches the
    `TextField,(Audio|Subtitle)<N>,<label>,...` pattern
  - maps human-readable language names ("English", "Castilian
    Spanish", "Brazilian Portuguese", "Canadian French", ...) to
    ISO 639-2 codes via a parser-local table (per the rules-of-
    engagement memo, each parser knows its own format)
  - preserves the full disc-authored label string in `name` so
    consumers display it raw without the lib guessing further
    structure
  - detects SDH / Forced qualifiers and Commentary / Descriptive
    purposes from substring matches; everything else falls through
    to fill_defaults using BD-spec MPLS data

Verified live on the corpus: disc-07 (Civil War UHD) now matches
parser=dbp with 3 audio + 2 subtitle labels, exactly the count
visible in the disc's authored TextField definitions and what BD
spec MPLS reports.

Limitation: dbp's detect() returns true for ANY top-level .jar in
/BDMV/JAR/ (every BD-J disc has one), since the discriminator
trait function takes only `&UdfFs` and can't read jar contents.
parse() does the real com/dbp/ check — a non-dbp disc gets
parsed-as-dbp, archive_has_dbp returns false, parse() returns
None, and we fall through. Diagnostic noise: parsers_detected
includes "dbp" on non-dbp BD-J discs. Real fix is refactoring the
DetectFn signature to take a SectorReader; deferred.

7 unit tests cover the TextField extraction, language detection
(simple + compound: "Brazilian Portuguese", "Castilian Spanish",
"Canadian French", "Latin American Spanish", "Australian English"
plus the disc-corpus typo "Austrailian English"), SDH/Forced/RNIB
qualifier detection, and Commentary/Descriptive purpose detection.
Don't-guess discipline preserved: unknown languages return ""
(consumer falls back to MPLS spec data via fill_defaults).

src/labels/mod.rs

@@ -9,6 +9,7 @@
 
 mod criterion;
 mod ctrm;
+mod dbp;
 mod paramount;
 mod pixelogic;
 pub mod vocab;
@@ -79,6 +80,12 @@ const PARSERS: &[(&str, DetectFn, ParseFn)] = &[
     ("criterion", criterion::detect, criterion::parse),
     ("pixelogic", pixelogic::detect, pixelogic::parse),
     ("ctrm", ctrm::detect, ctrm::parse),
+    // dbp last: detects on any top-level .jar in /BDMV/JAR/ (every
+    // BD-J disc has one), so parse() does the real `com/dbp/` check
+    // and returns None on a mismatch. By placing dbp last, the
+    // earlier parsers' fast file-presence detects short-circuit and
+    // dbp only runs on discs that fell through everything else.
+    ("dbp", dbp::detect, dbp::parse),
     // ("deluxe",  deluxe::detect,     deluxe::parse),  // TODO: bytecode parser
 ];