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

node_modules/next/dist/shared/lib/is-thenable.d.ts

@@ -0,0 +1,7 @@
+/**
+ * Check to see if a value is Thenable.
+ *
+ * @param promise the maybe-thenable value
+ * @returns true if the value is thenable
+ */
+export declare function isThenable<T = unknown>(promise: Promise<T> | T): promise is Promise<T>;