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/disc/extract.rs

@@ -234,9 +234,12 @@ impl Disc {
 
             // Acquire (rather than Relaxed) on these per-file delta loads:
             // `extract_tree` drives `dec` single-threaded so there is no race
-            // today, but Acquire costs nothing on x86 and gives a happens-
-            // before edge if file extraction is ever parallelised, so the
-            // delta can never read a torn/stale counter across iterations.
+            // today, and Acquire costs nothing on x86. Note this is only half
+            // the synchronisation: the paired counter store
+            // (sector/decrypting.rs `fetch_add`) is Relaxed, so an Acquire
+            // load alone does NOT yet establish a happens-before edge. Before
+            // file extraction is parallelised, upgrade that store to Release
+            // (or stronger) so the delta cannot read a stale counter.
             let before_loss = decrypt_loss.load(Ordering::Acquire);
             let (mut fr, halted) =
                 extract_one_file(&mut dec, dest, pf, total_bytes, &mut done_bytes, opts)?;