contractnumber provider added, old provider number field only if no previous contact exist

frontend/src/pages/contracts/ContractDetail.tsx

@@ -1569,6 +1569,12 @@ export default function ContractDetail() {
                 <dd className="font-mono">{c.previousContract.customerNumberAtProvider}</dd>
               </div>
             )}
+            {c.previousContract.contractNumberAtProvider && (
+              <div>
+                <dt className="text-sm text-gray-500">Vertragsnummer</dt>
+                <dd className="font-mono">{c.previousContract.contractNumberAtProvider}</dd>
+              </div>
+            )}
             {c.previousContract.portalUsername && (
               <div>
                 <dt className="text-sm text-gray-500">Zugangsdaten</dt>
@@ -1579,6 +1585,38 @@ export default function ContractDetail() {
         </Card>
       )}
 
+      {/* Altanbieter-Info (nur wenn KEIN Vorgängervertrag aber Altanbieter-Daten vorhanden) */}
+      {!c.previousContract && (c.previousProvider || c.previousCustomerNumber || c.previousContractNumber) && (
+        <Card className="mb-6 border-l-4 border-l-gray-400" title="Altanbieter">
+          <div className="grid grid-cols-2 md:grid-cols-4 gap-4">
+            {c.previousProvider && (
+              <div>
+                <dt className="text-sm text-gray-500">Anbieter</dt>
+                <dd>{c.previousProvider.name}</dd>
+              </div>
+            )}
+            {c.previousCustomerNumber && (
+              <div>
+                <dt className="text-sm text-gray-500">Kundennummer</dt>
+                <dd className="font-mono flex items-center gap-1">
+                  {c.previousCustomerNumber}
+                  <CopyButton value={c.previousCustomerNumber} />
+                </dd>
+              </div>
+            )}
+            {c.previousContractNumber && (
+              <div>
+                <dt className="text-sm text-gray-500">Vertragsnummer</dt>
+                <dd className="font-mono flex items-center gap-1">
+                  {c.previousContractNumber}
+                  <CopyButton value={c.previousContractNumber} />
+                </dd>
+              </div>
+            )}
+          </div>
+        </Card>
+      )}
+
       {/* Cancellation Confirmation Warning */}
       {c.cancellationConfirmationDate && (
         <div className="mb-6 p-4 bg-red-50 border-2 border-red-400 rounded-lg flex items-start gap-3">
@@ -1635,6 +1673,15 @@ export default function ContractDetail() {
                 </dd>
               </div>
             )}
+            {c.contractNumberAtProvider && (
+              <div>
+                <dt className="text-sm text-gray-500">Vertragsnummer</dt>
+                <dd className="font-mono flex items-center gap-1">
+                  {c.contractNumberAtProvider}
+                  <CopyButton value={c.contractNumberAtProvider} />
+                </dd>
+              </div>
+            )}
             {c.salesPlatform && (
               <div>
                 <dt className="text-sm text-gray-500">Vertriebsplattform</dt>