Add Better Auth admin authentication

app/login/page.tsx

@@ -1,12 +1,12 @@
 import { redirect } from "next/navigation";
 
 import { AuthEntry } from "@/components/auth-entry";
-import { getCurrentMockSession } from "@/lib/mock-session";
+import { isAuthenticated } from "@/lib/auth-server";
 
 export default async function LoginPage() {
-  const session = await getCurrentMockSession();
+  const isSessionActive = await isAuthenticated();
 
-  if (session) {
+  if (isSessionActive) {
     redirect("/dashboard");
   }