refactor: replace custom authentication middleware with NextAuth, remove unused authentication pages, and update matcher configuration

app/(auth)/auth/signup/page.tsx

@@ -1,5 +1,4 @@
 import SignUpForm from "@/components/auth/signup-form";
-import { getAtollsWithIslands } from "@/queries/atoll";
 import Image from "next/image";
 import { redirect } from "next/navigation";
 

app/api/auth/[...all]/route.ts

@@ -1,4 +0,0 @@
-import { auth } from "@/app/auth";
-import { toNextJsHandler } from "better-auth/next-js";
-
-export const { GET, POST } = toNextJsHandler(auth.handler);

app/api/auth/[...nextauth]/route.ts

@@ -0,0 +1,5 @@
+import { authOptions } from "@/app/auth";
+import NextAuth from "next-auth";
+
+const handler = NextAuth(authOptions);
+export { handler as GET, handler as POST };