feat: Add two-factor authentication via TOTP

Adds TOTP setup with QR code, login challenge, recovery codes and
trusted devices that let a browser skip the second factor for 30
days. Admins can reset another user's second factor by confirming
with their own password.

server/api/helpers/utils/generate-totp-secret.js

@@ -0,0 +1,16 @@
+/*!
+ * Copyright (c) 2024 PLANKA Software GmbH
+ * Licensed under the Fair Use License: https://github.com/plankanban/planka/blob/master/LICENSE.md
+ */
+
+const { authenticator } = require('otplib');
+
+module.exports = {
+  sync: true,
+
+  inputs: {},
+
+  fn() {
+    return authenticator.generateSecret();
+  },
+};