fix: wait for video metadata before playing and set onEnd before play

- Reorder onEnd callback before play() in Engine.goToScene to prevent
  missed ended event if video ends synchronously
- Wait for loadedmetadata event in VideoManager.play() before seeking
  to ensure currentTime reset works correctly on new video sources

engine/core/Engine.ts

@@ -46,13 +46,13 @@ export class Engine {
       this.stateManager.apply(scene.onEnter)
     }
 
-    this.videoManager.play(scene.videoUrl)
-    this.emit('sceneChange', scene)
-
     this.videoManager.onEnd(() => {
       this.emit('videoEnd', scene)
       this.onVideoEnd(scene)
     })
+
+    this.videoManager.play(scene.videoUrl)
+    this.emit('sceneChange', scene)
   }
 
   private onVideoEnd(scene: SceneNode) {

engine/core/VideoManager.ts

@@ -25,9 +25,22 @@ export class VideoManager {
     if (this.lastSrc !== src) {
       this.videoEl.src = src
       this.lastSrc = src
+      if (this.videoEl.readyState >= 1) {
+        this.videoEl.currentTime = 0
+        this.videoEl.play().catch(() => {})
+      } else {
+        const onReady = () => {
+          if (this.videoEl) {
+            this.videoEl.currentTime = 0
+            this.videoEl.play().catch(() => {})
+          }
+        }
+        this.videoEl.addEventListener('loadedmetadata', onReady, { once: true })
+      }
+    } else {
+      this.videoEl.currentTime = 0
+      this.videoEl.play().catch(() => {})
     }
-    this.videoEl.currentTime = 0
-    this.videoEl.play().catch(() => {})
   }
 
   pause() {