Member registration fixed

server/utils/members.js

@@ -221,14 +221,23 @@ export function normalizeDate(dateString) {
 }
 
 // Check for duplicate member based on firstName, lastName, and geburtsdatum
-function findDuplicateMember(members, firstName, lastName, geburtsdatum) {
-  const normalizedFirstName = (firstName || '').trim().toLowerCase()
-  const normalizedLastName = (lastName || '').trim().toLowerCase()
+function normalizeIdentityPart(value) {
+  return String(value || '')
+    .normalize('NFKD')
+    .replace(/[\u0300-\u036f]/g, '')
+    .replace(/[^a-zA-Z0-9]+/g, ' ')
+    .trim()
+    .toLowerCase()
+}
+
+export function findDuplicateMember(members, firstName, lastName, geburtsdatum) {
+  const normalizedFirstName = normalizeIdentityPart(firstName)
+  const normalizedLastName = normalizeIdentityPart(lastName)
   const normalizedDate = normalizeDate(geburtsdatum)
   
   return members.find(m => {
-    const mFirstName = (m.firstName || '').trim().toLowerCase()
-    const mLastName = (m.lastName || '').trim().toLowerCase()
+    const mFirstName = normalizeIdentityPart(m.firstName)
+    const mLastName = normalizeIdentityPart(m.lastName)
     const mDate = normalizeDate(m.geburtsdatum)
     
     return mFirstName === normalizedFirstName &&
@@ -307,4 +316,3 @@ export async function deleteMember(id) {
   await writeMembers(filtered)
   return true
 }
-