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

engine/types.ts

@@ -67,10 +67,19 @@ export interface QTEDefinition {
   }
 }
 
+export interface ChapterInfo {
+  id: string
+  label: string
+  startScene: string
+  thumbnail?: string
+  defaultVariables?: Record<string, number>
+}
+
 export interface GameData {
   scenes: Record<string, SceneNode>
   startScene: string
   variables: Record<string, number>
+  chapters?: ChapterInfo[]
 }
 
 export interface ChoiceRecord {
@@ -101,3 +110,4 @@ export type EngineEvent =
   | 'choiceTimeout'
   | 'hotspotRequest'
   | 'hotspotUpdate'
+  | 'chapterUnlock'