Implement member management enhancements; add bulk import functionality and duplicate checking based on geburtsdatum. Update API to support new fields and improve error handling for member data submissions. Refactor member-related components for better user experience and data validation.

server/utils/members.js

@@ -106,6 +106,37 @@ export async function getMemberById(id) {
   return members.find(m => m.id === id)
 }
 
+// Normalize date string for comparison (handles different date formats)
+export function normalizeDate(dateString) {
+  if (!dateString) return ''
+  // Try to parse and normalize to ISO format (YYYY-MM-DD)
+  try {
+    const date = new Date(dateString)
+    if (isNaN(date.getTime())) return dateString.trim()
+    return date.toISOString().split('T')[0]
+  } catch (e) {
+    return dateString.trim()
+  }
+}
+
+// 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()
+  const normalizedDate = normalizeDate(geburtsdatum)
+  
+  return members.find(m => {
+    const mFirstName = (m.firstName || '').trim().toLowerCase()
+    const mLastName = (m.lastName || '').trim().toLowerCase()
+    const mDate = normalizeDate(m.geburtsdatum)
+    
+    return mFirstName === normalizedFirstName &&
+           mLastName === normalizedLastName &&
+           mDate === normalizedDate &&
+           mDate !== '' // Only match if date is provided for both
+  })
+}
+
 // Add or update manual member
 export async function saveMember(memberData) {
   const members = await readMembers()
@@ -114,11 +145,37 @@ export async function saveMember(memberData) {
     // Update existing
     const index = members.findIndex(m => m.id === memberData.id)
     if (index !== -1) {
+      // Check for duplicate (excluding current member)
+      const duplicate = findDuplicateMember(
+        members.filter(m => m.id !== memberData.id),
+        memberData.firstName,
+        memberData.lastName,
+        memberData.geburtsdatum
+      )
+      
+      if (duplicate) {
+        throw new Error('Ein Mitglied mit diesem Namen und Geburtsdatum existiert bereits.')
+      }
+      
       members[index] = { ...members[index], ...memberData }
     } else {
       throw new Error('Mitglied nicht gefunden')
     }
   } else {
+    // Add new - check for duplicate first
+    if (memberData.firstName && memberData.lastName && memberData.geburtsdatum) {
+      const duplicate = findDuplicateMember(
+        members,
+        memberData.firstName,
+        memberData.lastName,
+        memberData.geburtsdatum
+      )
+      
+      if (duplicate) {
+        throw new Error('Ein Mitglied mit diesem Namen und Geburtsdatum existiert bereits.')
+      }
+    }
+    
     // Add new - use UUID for guaranteed uniqueness
     const newMember = {
       ...memberData,