Replace timestamp-based IDs with UUIDs for guaranteed uniqueness and race condition safety

server/utils/members.js

@@ -1,5 +1,6 @@
 import { promises as fs } from 'fs'
 import path from 'path'
+import { randomUUID } from 'crypto'
 
 // Handle both dev and production paths
 const getDataPath = (filename) => {
@@ -75,10 +76,10 @@ export async function saveMember(memberData) {
       throw new Error('Mitglied nicht gefunden')
     }
   } else {
-    // Add new
+    // Add new - use UUID for guaranteed uniqueness
     const newMember = {
-      id: `m${Date.now()}`,
-      ...memberData
+      ...memberData,
+      id: randomUUID() // Cryptographically secure unique ID
     }
     members.push(newMember)
   }