Stop automatic scrolling when moving the mouse away from the category

Adds a check to clear the existing scroll interval before starting a new one in the `startAutoScroll` function within the `CategoryRow` component.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 074b0e4c-6171-43bd-aa98-f9e04623ca14
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/8cc42625-c1f5-4e43-99bd-77f2c4dedee2/074b0e4c-6171-43bd-aa98-f9e04623ca14/6upLu3q

client/src/components/netflix-grid.tsx

@@ -155,6 +155,11 @@ function CategoryRow({ category, onVideoClick }: CategoryRowProps) {
   };
 
   const startAutoScroll = (direction: 'left' | 'right') => {
+    // Stop any existing scrolling first
+    if (scrollIntervalRef.current) {
+      clearInterval(scrollIntervalRef.current);
+    }
+    
     setIsScrolling(true);
     scrollIntervalRef.current = setInterval(() => {
       if (scrollRef.current) {