feat: P15 ending gallery, chapter recap, visited tracking, save system v6

engine/core/SceneManager.ts

@@ -25,6 +25,10 @@ export class SceneManager {
     return Object.keys(this.scenes)
   }
 
+  getScenes(): Record<string, SceneNode> {
+    return this.scenes
+  }
+
   getChapterBySceneId(sceneId: string): ChapterInfo | undefined {
     return this.chapters.find((ch) => ch.startScene === sceneId)
   }