feat: update layout and components for improved user experience, add theme toggle and main navigation

thoughts-frontend/components/main-nav.tsx

@@ -0,0 +1,22 @@
+"use client";
+
+import Link from "next/link";
+import { usePathname } from "next/navigation";
+import { cn } from "@/lib/utils";
+
+export function MainNav() {
+  const pathname = usePathname();
+  return (
+    <nav className="hidden md:flex items-center space-x-6 text-sm font-medium">
+      <Link
+        href="/"
+        className={cn(
+          "transition-colors hover:text-foreground/80",
+          pathname === "/" ? "text-foreground" : "text-foreground/60"
+        )}
+      >
+        Feed
+      </Link>
+    </nav>
+  );
+}