Chapters, DVD subtitle palette, MKV track flags, progress total_bytes

Chapters:
- MPLS PlayList marks parsed (mark_type 1 = chapter)
- Chapter struct on DiscTitle (time_secs, name)
- MKV Chapters element with EditionEntry/ChapterAtom per mark
- 3 MPLS mark tests + 2 MKV chapter tests

DVD subtitle palette:
- IFO palette extraction (PGC offset 0xA4, 16 × YCbCr colors)
- YCbCr→RGB conversion for VobSub .idx format
- DvdSubParser codec_private returns formatted palette
- codec_data field on SubtitleStream flows through pipeline
- 5 palette tests (YCbCr conversion, formatting, overflow)

MKV track flags:
- FlagDefault: primary video/audio = 1, secondary = 0
- FlagForced: forced subtitles = 1
- Language: set from stream language code
- Already implemented, verified with 4 new tests

Progress total_bytes:
- IOStream trait: total_bytes() -> Option<u64>
- DiscStream, IsoStream: from disc_title.size_bytes
- M2tsStream, MkvStream: from file metadata on open
- NetworkStream, StdioStream, NullStream: None

316 tests total, all passing.

src/disc/bluray.rs

@@ -128,6 +128,7 @@ impl Disc {
                                 codec,
                                 language: s.language.clone(),
                                 forced: false,
+                                codec_data: None,
                             }))
                         } else {
                             Some(Stream::Audio(AudioStream {
@@ -146,6 +147,7 @@ impl Disc {
                         codec,
                         language: s.language.clone(),
                         forced: false,
+                        codec_data: None,
                     })),
                     // Stream type 4 = IG, unknown types -- skip
                     _ => None,
@@ -153,6 +155,22 @@ impl Disc {
             })
             .collect();
 
+        // Convert marks to chapters (filter mark_type == 1 = chapter entry)
+        let first_in_time = parsed.play_items.first().map(|pi| pi.in_time).unwrap_or(0);
+        let chapters: Vec<Chapter> = parsed
+            .marks
+            .iter()
+            .filter(|m| m.mark_type == 1)
+            .enumerate()
+            .map(|(i, m)| {
+                let time_secs = (m.timestamp as f64 - first_in_time as f64) / 45000.0;
+                Chapter {
+                    time_secs: if time_secs < 0.0 { 0.0 } else { time_secs },
+                    name: format!("Chapter {}", i + 1),
+                }
+            })
+            .collect();
+
         let playlist_num = filename.trim_end_matches(".mpls").trim_end_matches(".MPLS");
         let playlist_id = playlist_num.parse::<u16>().unwrap_or(0);
 
@@ -163,6 +181,7 @@ impl Disc {
             size_bytes: total_size,
             clips,
             streams,
+            chapters,
             extents,
             content_format: ContentFormat::BdTs,
         })