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/undefsafe/example.js

@@ -0,0 +1,14 @@
+var undefsafe = require('undefsafe');
+
+var object = {
+  a: {
+    b: {
+      c: 1,
+      d: [1, 2, 3],
+      e: 'remy'
+    }
+  }
+};
+
+console.log(undefsafe(object, 'a.b.e')); // "remy"
+console.log(undefsafe(object, 'a.b.not.found')); // undefined