feat: video loop support for hotspot scenes, demo updates, docs, and engine fixes

engine/core/VideoManager.ts

@@ -149,6 +149,11 @@ export class VideoManager {
     return this.active ?? null
   }
 
+  seekTo(time: number) {
+    if (!this.active) return
+    this.active.currentTime = time
+  }
+
   onEnd(cb: VideoEndCallback) {
     this.onEndCallback = cb
   }