feat: implement category flags, drop global tables, fix sidebar sticky layout

shop/app/api/orders/checkout/route.ts

@@ -8,6 +8,8 @@ import { renderToBuffer } from '@react-pdf/renderer';
 import React from 'react';
 import { InvoicePDF } from '@/components/invoice-pdf';
 import { getOrderEmailTemplate, buildEmailItemsSection } from '@/lib/actions/email-templates';
+import { validateWizardSelections } from '@/lib/actions/validation';
+
 
 function generateOrderNumber(prefix: 'BE' | 'AE' = 'AE'): string {
   const year = new Date().getFullYear();
@@ -49,6 +51,13 @@ export async function POST(request: Request) {
     const products = await getProducts();
     const categories = await getCategories();
 
+    // --- Backend-Validierung: alle Kategorie-Flags für jede Kasse prüfen ---
+    for (const item of items) {
+      if (item.selections) {
+        validateWizardSelections(item.selections, products, categories);
+      }
+    }
+
     // Split items into purchase and subscription
     const purchaseItems = items.filter(
       (item: any) => item.billingInterval === 'one_time' || item.billingType === 'purchase'