feat: chapter select system, multi-chapter support, scene manager refactor, and docs update

engine/core/SceneManager.ts

@@ -1,12 +1,14 @@
-import type { GameData, SceneNode, Choice, Condition } from '../types'
+import type { GameData, SceneNode, ChapterInfo, Choice, Condition } from '../types'
 
 export class SceneManager {
   private scenes: Record<string, SceneNode> = {}
   private startScene: string = ''
+  chapters: ChapterInfo[] = []
 
   load(data: GameData) {
     this.scenes = data.scenes
     this.startScene = data.startScene
+    this.chapters = data.chapters || []
   }
 
   getScene(id: string): SceneNode | undefined {
@@ -23,6 +25,14 @@ export class SceneManager {
     return Object.keys(this.scenes)
   }
 
+  getChapterBySceneId(sceneId: string): ChapterInfo | undefined {
+    return this.chapters.find((ch) => ch.startScene === sceneId)
+  }
+
+  getChapter(chapterId: string): ChapterInfo | undefined {
+    return this.chapters.find((ch) => ch.id === chapterId)
+  }
+
   getCandidateTargetIds(scene: SceneNode, evaluateCondition: (conds?: Condition[]) => boolean): string[] {
     const targets: string[] = []