feat(ui): tune mobile active state and fix desktop regression

- Relax `VideoCard` active state detection to a 30% viewport sweet spot (rootMargin -35%)
- Strict desktop detection using `window.matchMedia` to prevent active state conflicts
- Encapsulate mobile active CSS rules within media query to prevent desktop style leakage
- Fix mobile layout overflow issues by enforcing `min-width: 0`
- Ensure marquee scrolling effect is robustly toggled based on overflow detection

js/ui/components/VideoCard.js

@@ -3063,7 +3063,7 @@ export class VideoCard {
             }
           }
         },
-        { rootMargin: "-45% 0px -45% 0px", threshold: 0 }
+        { rootMargin: "-35% 0px -35% 0px", threshold: 0 }
       );
     }
     VideoCard.viewportObserver.observe(element);