Fix test failures: correct EBML size assertion, fix doc tests

- Fix write_size test: 127 encodes as [0x40, 0x7F] not [0xC0, 0x7F]
- Mark doc examples as ignore (use incomplete pseudo-code)

src/event.rs

@@ -4,7 +4,7 @@
 //! The app registers a callback to receive them.
 //! No display logic, no English text — just data.
 //!
-//! ```rust
+//! ```rust,ignore
 //! disc.rip(&mut session, 0, output, |event| {
 //!     match event.kind {
 //!         EventKind::BytesRead { bytes, total } => update_progress(bytes, total),

src/mux/ebml.rs

@@ -234,7 +234,7 @@ mod tests {
 
         buf.clear();
         write_size(&mut buf, 127).unwrap();
-        assert_eq!(buf, [0xC0, 127]); // 127 >= 0x7F, uses 2 bytes
+        assert_eq!(buf, [0x40, 127]); // 127 >= 0x7F, uses 2 bytes: (0>>8)|0x40, 127
 
         buf.clear();
         write_size(&mut buf, 126).unwrap();

src/mux/stream.rs

@@ -1,6 +1,6 @@
 //! MkvStream — a Write adapter that demuxes BD-TS and writes MKV.
 //!
-//! ```rust
+//! ```rust,ignore
 //! let output = MkvStream::new(file)
 //!     .title(&disc.titles[0])
 //!     .max_buffer(20 * 1024 * 1024);