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/string-length/index.d.ts

@@ -0,0 +1,22 @@
+/**
+Get the real length of a string - by correctly counting astral symbols and ignoring [ansi escape codes](https://github.com/sindresorhus/strip-ansi).
+
+`String#length` erroneously counts [astral symbols](https://web.archive.org/web/20150721114550/http://www.tlg.uci.edu/~opoudjis/unicode/unicode_astral.html) as two characters.
+
+@example
+```
+import stringLength = require('string-length');
+
+'🐴'.length;
+//=> 2
+
+stringLength('🐴');
+//=> 1
+
+stringLength('\u001B[1municorn\u001B[22m');
+//=> 7
+```
+*/
+declare function stringLength(string: string): number;
+
+export = stringLength;