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/fast-safe-stringify/index.d.ts

@@ -0,0 +1,23 @@
+declare function stringify(
+  value: any,
+  replacer?: (key: string, value: any) => any,
+  space?: string | number,
+  options?: { depthLimit: number | undefined; edgesLimit: number | undefined }
+): string;
+
+declare namespace stringify {
+  export function stable(
+    value: any,
+    replacer?: (key: string, value: any) => any,
+    space?: string | number,
+    options?: { depthLimit: number | undefined; edgesLimit: number | undefined }
+  ): string;
+  export function stableStringify(
+    value: any,
+    replacer?: (key: string, value: any) => any,
+    space?: string | number,
+    options?: { depthLimit: number | undefined; edgesLimit: number | undefined }
+  ): string;
+}
+
+export default stringify;