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/iconv-lite/lib/bom-handling.js

@@ -0,0 +1,48 @@
+"use strict"
+
+var BOMChar = "\uFEFF"
+
+exports.PrependBOM = PrependBOMWrapper
+function PrependBOMWrapper (encoder, options) {
+  this.encoder = encoder
+  this.addBOM = true
+}
+
+PrependBOMWrapper.prototype.write = function (str) {
+  if (this.addBOM) {
+    str = BOMChar + str
+    this.addBOM = false
+  }
+
+  return this.encoder.write(str)
+}
+
+PrependBOMWrapper.prototype.end = function () {
+  return this.encoder.end()
+}
+
+// ------------------------------------------------------------------------------
+
+exports.StripBOM = StripBOMWrapper
+function StripBOMWrapper (decoder, options) {
+  this.decoder = decoder
+  this.pass = false
+  this.options = options || {}
+}
+
+StripBOMWrapper.prototype.write = function (buf) {
+  var res = this.decoder.write(buf)
+  if (this.pass || !res) { return res }
+
+  if (res[0] === BOMChar) {
+    res = res.slice(1)
+    if (typeof this.options.stripBOM === "function") { this.options.stripBOM() }
+  }
+
+  this.pass = true
+  return res
+}
+
+StripBOMWrapper.prototype.end = function () {
+  return this.decoder.end()
+}