Holiday music: a dark carol for Christmas, a spring tune for Easter, a harpsichord dance for Halloween

During a holiday the title music plays its piece, the build music every fourth time.

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

src/tracks.rs

@@ -3,7 +3,7 @@
 
 use crate::audio::Category;
 
-pub const TRACKS: [(&str, Category, &[u8]); 47] = [
+pub const TRACKS: [(&str, Category, &[u8]); 50] = [
     ("title", Category::Title, include_bytes!("../assets/music/title.xm")),
     ("title2", Category::Title, include_bytes!("../assets/music/title2.xm")),
     ("build1", Category::Build, include_bytes!("../assets/music/build1.xm")),
@@ -51,4 +51,7 @@ pub const TRACKS: [(&str, Category, &[u8]); 47] = [
     ("victory", Category::Victory, include_bytes!("../assets/music/victory.xm")),
     ("victory2", Category::Victory, include_bytes!("../assets/music/victory2.xm")),
     ("defeat", Category::Defeat, include_bytes!("../assets/music/defeat.xm")),
+    ("holiday_christmas", Category::Christmas, include_bytes!("../assets/music/holiday_christmas.xm")),
+    ("holiday_easter", Category::Easter, include_bytes!("../assets/music/holiday_easter.xm")),
+    ("holiday_halloween", Category::Halloween, include_bytes!("../assets/music/holiday_halloween.xm")),
 ];