feat: update dependencies and refactor layout and homepage components

- Added new dependencies: @daveyplate/better-auth-ui, next-themes, and sonner.
- Refactored layout component to use Providers and Toaster for better state management and notifications.
- Updated homepage to utilize authClient for session management and improved user experience with navigation links for sign-in and sign-up.

components/providers.tsx

@@ -0,0 +1,40 @@
+"use client";
+
+import { ReactNode } from "react";
+import { ConvexReactClient } from "convex/react";
+import { ConvexBetterAuthProvider } from "@convex-dev/better-auth/react";
+import { AuthUIProvider } from "@daveyplate/better-auth-ui";
+import Link from "next/link";
+import { useRouter } from "next/navigation";
+
+import { authClient } from "@/lib/auth-client";
+
+const convex = new ConvexReactClient(process.env.NEXT_PUBLIC_CONVEX_URL!);
+
+export function Providers({
+  children,
+  initialToken,
+}: {
+  children: ReactNode;
+  initialToken?: string | null;
+}) {
+  const router = useRouter();
+
+  return (
+    <ConvexBetterAuthProvider
+      client={convex}
+      authClient={authClient}
+      initialToken={initialToken}
+    >
+      <AuthUIProvider
+        authClient={authClient}
+        navigate={router.push}
+        replace={router.replace}
+        onSessionChange={() => router.refresh()}
+        Link={Link}
+      >
+        {children}
+      </AuthUIProvider>
+    </ConvexBetterAuthProvider>
+  );
+}