Holidays: Christmas and Easter beside Halloween, two weeks before to a few days after; decorations in the dungeon and around the title

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

src/main.rs

@@ -19,6 +19,7 @@ mod fog;
 mod fortress;
 mod game;
 mod gfx;
+mod holiday;
 mod i18n;
 mod lobby;
 mod map;