feat: Passwordless cross-device authentication

- Arkitektur: docs/auth/passwordless-architecture.md
- Backend: iom/quixzoom-auth-service/ (FastAPI + Redis)
- Webb: quixzoom-market-pages/se/login/ (QR-kod + polling)
- App: iom/quixzoom-app/src/features/auth/ (push + deep links)

Flöde: QR-kod → app-godkännande → webb-inloggad

landvex/node_modules/validator/lib/util/assertString.js

@@ -0,0 +1,12 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = assertString;
+function assertString(input) {
+  if (input === undefined || input === null) throw new TypeError("Expected a string but received a ".concat(input));
+  if (input.constructor.name !== 'String') throw new TypeError("Expected a string but received a ".concat(input.constructor.name));
+}
+module.exports = exports.default;
+module.exports.default = exports.default;