refactor: migrate authentication and signup flow to use external API and improve type safety

queries/atoll.ts

@@ -0,0 +1,10 @@
+"use server";
+
+import type { Atoll, DataResponse } from "@/lib/backend-types";
+
+export async function getAtollsWithIslands(): Promise<DataResponse<Atoll>> {
+	const response = await fetch(
+		`${process.env.SARLINK_API_BASE_URL}/api/auth/atolls`,
+	);
+	return response.json();
+}