fix: restore sidebar in dashboard layout

src/app/(dashboard)/layout.tsx

@@ -1,3 +1,12 @@
+import { Sidebar } from @/components/layout/Sidebar;
+
 export default function DashboardLayout({ children }: { children: React.ReactNode }) {
-  return <>{children}</>;
+  return (
+    <div className=flex h-screen overflow-hidden>
+      <Sidebar />
+      <div className=flex-1 overflow-y-auto>
+        {children}
+      </div>
+    </div>
+  );
 }