fix(sidebar): prevent overflow in SidebarSeparator with horizontal orientation

Updated SidebarSeparator component to use `data-[orientation=horizontal]:w-auto` instead of `w-auto` to prevent overflow issues caused by underlying Separator classes.

The change makes the width override more specific, only applying to horizontal separators, which prevents conflicts with other Separator styling.

This change is applied to apps/v4 (apps/www is deprecated).

Author: edouard-andrei

apps/v4/registry/new-york-v4/ui/sidebar.tsx

@@ -362,7 +362,10 @@ function SidebarSeparator({
     <Separator
       data-slot="sidebar-separator"
       data-sidebar="separator"
-      className={cn("bg-sidebar-border mx-2 w-auto", className)}
+      className={cn(
+        "bg-sidebar-border mx-2 data-[orientation=horizontal]:w-auto",
+        className
+      )}
       {...props}
     />
   )