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.

Author: edouard-andrei

apps/v4/__registry__/index.ts

@@ -12,7 +12,7 @@ const props = defineProps<{
   <Separator
     data-slot="sidebar-separator"
     data-sidebar="separator"
-    :class="cn('bg-sidebar-border mx-2 w-auto', props.class)"
+    :class="cn('bg-sidebar-border mx-2 data-[orientation=horizontal]:w-auto', props.class)"
   >
     <slot />
   </Separator>