feat(api): add create and update product routes with authentication

refactor(admin): integrate router refresh after product updates in forms
fix(imports): update fetch paths for product creation and update in ReceiptImportClient

frontend/app/kvitto/ReceiptImportClient.tsx

@@ -196,7 +196,7 @@ export default function ReceiptImportClient({ isAdmin }: { isAdmin: boolean }) {
     console.log('handleCreateProduct: isAdmin =', isAdmin, 'endpoint = /api/products-create');
     try {
       // Admin skapar aktiv produkt via API route
-      const res = await fetch('/api/products-create', {
+      const res = await fetch('/api/admin/create-product', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({ name: row.rawName }),
@@ -212,7 +212,7 @@ export default function ReceiptImportClient({ isAdmin }: { isAdmin: boolean }) {
       // Sätt kategori: AI-förslag har prioritet, annars manuellt val
       const categoryId = row.categorySuggestion?.categoryId ?? (row.selectedCategoryId !== '' ? row.selectedCategoryId : null);
       if (categoryId) {
-        const patchRes = await fetch(`/api/products-update/${product.id}`, {
+        const patchRes = await fetch(`/api/admin/update-product/${product.id}`, {
           method: 'PATCH',
           headers: { 'Content-Type': 'application/json' },
           body: JSON.stringify({ categoryId }),