DVD vob_start absolute rebase + rc.5.3 audit fixes

- ifo.rs: rebase VTS title VOBS to absolute disc LBA (file_start_lba +
  vtstt_vobs); fixes DVD rips opening on the menu region instead of the
  movie (e.g. SOTL). Adds absolute-placement regression test.
- aacs/boil.rs: add mk_from_pk primitive (PK -> MK via MKB walk).
- dvdnav/: nav-VM command decoder + start-cell resolver seam, parked
  behind USE_NAV_RESOLVER (kept compiled, never executed).
- mux: FVI src.byte within-sector per spec; Unknown colour -> CICP
  unspecified (2,2,2,1); demux clear PCS -> NORMAL; ts.rs feed() base
  reset + boundary provenance fix.
- Assorted audit fixes (doc/comment/test accuracy) across the crate.

src/error.rs

@@ -1199,6 +1199,7 @@ mod tests {
             E_NO_DISC_KEY,
             E_CSS_KEY_MISSING,
             E_AACS_NO_HOST_CERT,
+            E_AACS_BUS_KEY_UNAVAILABLE,
             E_KEYDB_CONNECT,
             E_KEYDB_HTTP,
             E_KEYDB_INVALID,