feat(customers): add customer-level and device-level update/upgrade buttons with automatic license date calculation for update discount

shop/app/my-customers/[id]/page.tsx

@@ -104,6 +104,13 @@ export default function CustomerDetailPage({ params }: { params: Promise<{ id: s
               Kunden-ID: <span className="font-mono">{customer.id.slice(0, 8)}…</span>
             </p>
           </div>
+          {!customer.is_anonymized && (
+            <Link href={`/order?customer_id=${customer.id}`} className="ml-auto">
+              <Button size="sm" className="bg-primary hover:bg-primary/90 text-white font-bold gap-2 shadow-[0_0_15px_rgba(59,130,246,0.3)] text-xs">
+                <ShoppingBag className="w-4 h-4" /> Kunde updaten / bestellen
+              </Button>
+            </Link>
+          )}
           {customer.is_anonymized && (
             <Badge className="bg-red-500/10 text-red-400 border-red-500/20 gap-1 ml-auto">
               <AlertTriangle className="w-3 h-3" /> Anonymisiert