add login/sign-up page with dark/light mode

node_modules/is-async-function/index.d.ts

@@ -0,0 +1,9 @@
+import type { AsyncFunction } from 'async-function';
+
+declare namespace isAsyncFunction {
+    export type { AsyncFunction };
+}
+
+declare function isAsyncFunction(fn: unknown): fn is AsyncFunction;
+
+export = isAsyncFunction;