🐛(frontend) fix modal overflow when stopping processors in join screen

Fixes visual glitch where processor termination caused height increase
beyond modal boundaries, ensuring consistent modal dimensions
regardless of processor state changes.

src/frontend/src/features/rooms/livekit/components/effects/EffectsConfiguration.tsx

@@ -180,6 +180,8 @@ export const EffectsConfiguration = ({
           width: '100%',
           aspectRatio: 16 / 9,
           position: 'relative',
+          overflow: 'hidden',
+          borderRadius: '8px',
         })}
       >
         {videoTrack && !videoTrack.isMuted ? (