refactor for shared states and multi chapters

assets/js/games/scenes/system-shutdown-1999/art/index.js

@@ -0,0 +1,33 @@
+// Art assets index for System Shutdown: 1999 series
+// These reference the ANSI art defined in ascii-art.js
+
+// Art constants are loaded from ascii-art.js and made available globally
+// This file provides a namespace for the series' art assets
+
+window.SystemShutdown1999Art = window.SystemShutdown1999Art || {};
+
+// These will be populated by ascii-art.js when it loads
+// The art constants are:
+// - BOXING_DAY_TITLE: Chapter 1 title screen
+// - DARK_TOWER_HEADER: Dark Tower BBS header
+// - LIGHTHOUSE_HEADER: The Lighthouse BBS header
+
+// Helper to get art by name
+window.SystemShutdown1999Art.get = function (name) {
+  switch (name) {
+    case "BOXING_DAY_TITLE":
+      return window.BOXING_DAY_TITLE;
+    case "DARK_TOWER_HEADER":
+      return window.DARK_TOWER_HEADER;
+    case "LIGHTHOUSE_HEADER":
+      return window.LIGHTHOUSE_HEADER;
+    default:
+      console.warn(`Unknown art asset: ${name}`);
+      return null;
+  }
+};
+
+// List available art assets
+window.SystemShutdown1999Art.list = function () {
+  return ["BOXING_DAY_TITLE", "DARK_TOWER_HEADER", "LIGHTHOUSE_HEADER"];
+};