Improve sidebar toggle button appearance and responsiveness on mobile

Update sidebar toggle button styling in client/src/components/sidebar.tsx to include a border and adjust hover effects, improving its appearance and fitting better within the mobile layout.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/ZZqfJdr

client/src/components/sidebar.tsx

@@ -305,7 +305,7 @@ export default function Sidebar() {
         {/* Toggle Button */}
         <button
           onClick={() => setIsCollapsed(!isCollapsed)}
-          className="mt-2 w-full flex items-center justify-center p-2 text-muted-foreground hover:text-primary hover:bg-sidebar-accent rounded-xl transition-all"
+          className="mt-2 w-full flex items-center justify-center p-2 text-muted-foreground hover:text-primary hover:bg-primary/10 border-2 border-border hover:border-primary/50 rounded-xl transition-all"
           data-testid="button-toggle-sidebar"
         >
           {isCollapsed ? <ChevronRight className="w-5 h-5" /> : <ChevronLeft className="w-5 h-5" />}