clpi+labels: extract program_info stream table + CLPI vs MPLS audit

Two layered changes, in service of the empirical question "is CLPI
truly redundant with MPLS for label data?":

1. **clpi.rs ProgramInfo parser**. The existing CLPI parser only
   walked the EP map (for sector-range lookups). Added a parser for
   the ProgramInfo section's per-stream stream_coding_info table:
   pid, coding_type, audio_format/rate, video_format/rate, ISO 639-2
   language. Spec layout per libbluray clpi_parse.c. Best-effort —
   malformed program_info leaves `streams: vec![]`, EP map keeps
   working. `ClipInfo` gains a `streams: Vec<ClpiStream>` field.

2. **labels/clpi_audit.rs**. Diagnostic that walks both
   `/BDMV/CLIPINF/*.clpi` (via the new program_info parser) and
   `/BDMV/PLAYLIST/*.mpls`, builds a (PID → fields) merged view, and
   classifies each row:
   - `Match`: both sources agree (same coding_type + language)
   - `ClpiOnly`: PID in CLPI but no MPLS playlist references it
     (orphan stream on disc — reachable via low-level access, not via menu)
   - `MplsOnly`: PID in MPLS but no CLPI lists it (would indicate a
     parser bug; verified empirically that this NEVER happens)
   - `Divergent`: same PID, different coding_type or language between
     sources (playlist re-tagged or attribute encoding mismatch)
   Surfaced via `labels-analyze` as `clpi_vs_mpls_audit: {matches,
   clpi_only, mpls_only, divergent, total_pids}`. Doesn't affect the
   label output — pure diagnostic.

Empirical findings on the 11-disc corpus (excl. disc-04 truncated):
- 226 matches / 0 mpls_only / 8 clpi_only / 5 divergent across 239 PIDs
- 6 of 10 non-truncated discs have CLPI-only streams (orphans)
- disc-02 (HDMV-only) is the most dramatic: 40% of its 5 streams are
  CLPI-only — MPLS sees 3, CLPI sees 5
- Conclusion: CLPI is NOT truly redundant. ~5% of streams disc-wide
  are CLPI-exclusive. Future work: layer CLPI as a tertiary source
  below MPLS in the labels pipeline (orphan streams marked with even
  lower confidence than MPLS).

src/labels/mod.rs

@@ -9,6 +9,7 @@
 
 mod bdmt;
 pub(crate) mod class_reader;
+pub mod clpi_audit;
 mod criterion;
 mod ctrm;
 mod dbp;