Enhance debug logging and Cross-Device support for Passkey Registration

Update the registrieren.vue component to include detailed debug statements for the Cross-Device authentication flow, specifically during QR-Code generation. Improve logging in the register-passkey-options and register-passkey APIs to capture request details such as user agent and IP address, aiding in troubleshooting. Additionally, introduce a new function to retrieve pre-registration data, enhancing the overall registration process and compliance with Cross-Device requirements.

server/utils/webauthn-challenges.js

@@ -59,4 +59,12 @@ export function consumePreRegistration(registrationId) {
   return v.payload || null
 }
 
+export function getPreRegistration(registrationId) {
+  cleanup(preRegChallenges)
+  const key = String(registrationId)
+  const v = preRegChallenges.get(key)
+  if (!v) return null
+  return v.payload || null
+}
+