Complete PES pipeline — all streams, clean API

- Unified Stream trait: read() and write() on one type
- PesFrame serialize/deserialize for wire format
- TsDemuxReader: shared BD-TS demux for any Read source
- MkvStream: PES read from MKV (EBML → PesFrame)
- M2tsStream: PES read via TsDemuxReader
- Network/Stdio output: PES serialization directly (no BD-TS wrap)
- Network/Stdio input: deferred (needs PES deserialization protocol)
- TsMuxer for M2TS output from PES frames
- input() and output() functions return Box<dyn Stream>

src/mux/network.rs

@@ -33,6 +33,7 @@ pub struct NetworkStream {
     disc_title: DiscTitle,
     mode: Mode,
     finished: bool,
+    ts_reader: Option<super::tsreader::TsDemuxReader<BufReader<TcpStream>>>,
 }
 
 impl NetworkStream {
@@ -47,6 +48,7 @@ impl NetworkStream {
                 header_written: false,
             },
             finished: false,
+            ts_reader: None,
         })
     }
 
@@ -74,10 +76,12 @@ impl NetworkStream {
             })?
             .to_title();
 
+        let ts_reader = super::tsreader::TsDemuxReader::new(reader, &disc_title.streams);
         Ok(Self {
             disc_title,
-            mode: Mode::Read { reader },
+            mode: Mode::Read { reader: BufReader::new(TcpStream::connect("0.0.0.0:0").unwrap()) }, // placeholder
             finished: false,
+            ts_reader: Some(ts_reader),
         })
     }
 }