fix: checkQTE guard against stale scene closures

Since onTimeUpdate callbacks are now additive (Set), goToScene closures
for old scenes persist. Add currentScene?.id !== scene.id check to
prevent QTE from re-triggering for past scenes after scene transitions.

engine/core/Engine.ts

@@ -85,6 +85,7 @@ export class Engine {
   }
 
   private checkQTE(scene: SceneNode, time: number) {
+    if (this.currentScene?.id !== scene.id) return
     if (!scene.qte || this.qteTriggered) return
     if (time >= scene.qte.triggerTime) {
       this.qteTriggered = true