Music: six more dungeon pieces and six surface pieces with flute, harp, birdsong and wind

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/xm.rs

@@ -1130,7 +1130,7 @@ mod tests {
     fn render_all_songs() {
         for (k, (name, _, data)) in crate::tracks::TRACKS.iter().enumerate() {
             let m = Rc::new(load(data).expect("load"));
-            assert_eq!(m.channels, 8, "{}", name);
+            assert!(m.channels == 8 || (m.channels == 10 && name.starts_with("surface")), "{} {}", name, m.channels);
             let mut p = Player::new(m, 48000.0);
             let mut buf = vec![0.0f32; 48000 * 2];
             let mut peak = 0.0f32;