Fix all v4 audit findings (22 items)

HIGH: ISO writer multi-extent for >4GB, end-to-end MKV mux test
MEDIUM: AACS cvalue bounds, UV offset, macOS discovery, VC-1 resolution
  from sequence header, HEVC profile flags from SPS, ISO CRC + reserve AVDP
LOW: PS AC3 sub-header, CSS crack first-match break, TrackUID unique,
  AC3 no-sync empty return, --all for iso://, --min warning, dead code removed

320 tests, all passing.

src/css/crack.rs

@@ -150,8 +150,12 @@ pub fn recover_title_key(sector: &[u8], plain: &[u8]) -> Option<[u8; 5]> {
                 result_key[3] = ((val >> 8) & 0xFF) as u8;
                 result_key[4] = ((val >> 16) & 0xFF) as u8;
                 found = true;
+                break;
             }
         }
+        if found {
+            break;
+        }
     }
 
     if !found {