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/path-exists/index.d.ts

@@ -0,0 +1,28 @@
+declare const pathExists: {
+	/**
+	Check if a path exists.
+
+	@returns Whether the path exists.
+
+	@example
+	```
+	// foo.ts
+	import pathExists = require('path-exists');
+
+	(async () => {
+		console.log(await pathExists('foo.ts'));
+		//=> true
+	})();
+	```
+	*/
+	(path: string): Promise<boolean>;
+
+	/**
+	Synchronously check if a path exists.
+
+	@returns Whether the path exists.
+	*/
+	sync(path: string): boolean;
+};
+
+export = pathExists;