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/moment/src/lib/duration/add-subtract.js

@@ -0,0 +1,21 @@
+import { createDuration } from './create';
+
+function addSubtract(duration, input, value, direction) {
+    var other = createDuration(input, value);
+
+    duration._milliseconds += direction * other._milliseconds;
+    duration._days += direction * other._days;
+    duration._months += direction * other._months;
+
+    return duration._bubble();
+}
+
+// supports only 2.0-style add(1, 's') or add(duration)
+export function add(input, value) {
+    return addSubtract(this, input, value, 1);
+}
+
+// supports only 2.0-style subtract(1, 's') or subtract(duration)
+export function subtract(input, value) {
+    return addSubtract(this, input, value, -1);
+}