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/get-stream/index.js

@@ -0,0 +1,61 @@
+'use strict';
+const {constants: BufferConstants} = require('buffer');
+const stream = require('stream');
+const {promisify} = require('util');
+const bufferStream = require('./buffer-stream');
+
+const streamPipelinePromisified = promisify(stream.pipeline);
+
+class MaxBufferError extends Error {
+	constructor() {
+		super('maxBuffer exceeded');
+		this.name = 'MaxBufferError';
+	}
+}
+
+async function getStream(inputStream, options) {
+	if (!inputStream) {
+		throw new Error('Expected a stream');
+	}
+
+	options = {
+		maxBuffer: Infinity,
+		...options
+	};
+
+	const {maxBuffer} = options;
+	const stream = bufferStream(options);
+
+	await new Promise((resolve, reject) => {
+		const rejectPromise = error => {
+			// Don't retrieve an oversized buffer.
+			if (error && stream.getBufferedLength() <= BufferConstants.MAX_LENGTH) {
+				error.bufferedData = stream.getBufferedValue();
+			}
+
+			reject(error);
+		};
+
+		(async () => {
+			try {
+				await streamPipelinePromisified(inputStream, stream);
+				resolve();
+			} catch (error) {
+				rejectPromise(error);
+			}
+		})();
+
+		stream.on('data', () => {
+			if (stream.getBufferedLength() > maxBuffer) {
+				rejectPromise(new MaxBufferError());
+			}
+		});
+	});
+
+	return stream.getBufferedValue();
+}
+
+module.exports = getStream;
+module.exports.buffer = (stream, options) => getStream(stream, {...options, encoding: 'buffer'});
+module.exports.array = (stream, options) => getStream(stream, {...options, array: true});
+module.exports.MaxBufferError = MaxBufferError;