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

node_modules/http-proxy-middleware/dist/plugins/define-plugin.js

@@ -0,0 +1,25 @@
+/**
+ * Helper function to define a http-proxy-middleware plugin
+ * @see proxyServer {@link ProxyServer} - proxy server instance to which the plugin is being applied
+ * @see options {@link Options} - options object passed to `createProxyMiddleware`
+ *
+ * @example defining a plugin
+ * ```js
+ * export const myPlugin = definePlugin((proxyServer, options) => {
+ *   // plugin implementation
+ * });
+ * ```
+ *
+ * @example using a plugin
+ * ```js
+ * createProxyMiddleware({
+ *   target: 'http://example.com',
+ *   plugins: [myPlugin],
+ * });
+ * ```
+ *
+ * @since 4.1.0
+ */
+export function definePlugin(fn) {
+    return fn;
+}