Merge pull request #2297 from PR0M3TH3AN/claude/improve-playwright-testability-8mNO7

Add Playwright agent testing infrastructure with test harness and mock relay

js/ui/components/VideoCard.js

@@ -393,6 +393,7 @@ export class VideoCard {
     VideoCard.observeViewport(this.root);
 
     this.root.dataset.component = "video-card";
+    this.root.dataset.testid = "video-card";
     this.syncCardState();
     this.syncMotionState();
     if (this.video?.id) {