fix(tree): sort category nodes by name in flattenTree function

frontend/app/admin/products/AdminProductList.tsx

@@ -18,7 +18,8 @@ const sortOptions = [
 
 function flattenTree(nodes: CategoryNode[], depth = 0): { id: number; label: string }[] {
   const result: { id: number; label: string }[] = [];
-  for (const node of nodes) {
+  const sorted = [...nodes].sort((a, b) => a.name.localeCompare(b.name, 'sv'));
+  for (const node of sorted) {
     result.push({ id: node.id, label: '\u00a0\u00a0'.repeat(depth) + (depth > 0 ? '↳ ' : '') + node.name });
     if (node.children?.length) result.push(...flattenTree(node.children, depth + 1));
   }

frontend/app/admin/products/EditProductForm.tsx

@@ -53,7 +53,8 @@ export default function EditProductForm({ product }: Props) {
   // Bygg flat lista för select med indragna nivåer
   function flattenTree(nodes: CategoryNode[], depth = 0): { id: number; name: string; label: string }[] {
     const result: { id: number; name: string; label: string }[] = [];
-    for (const node of nodes) {
+    const sorted = [...nodes].sort((a, b) => a.name.localeCompare(b.name, 'sv'));
+    for (const node of sorted) {
       const prefix = depth === 0 ? '' : depth === 1 ? '\u00a0\u00a0\u00a0↳ ' : '\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0↳ ';
       result.push({ id: node.id, name: node.name, label: prefix + node.name });
       result.push(...flattenTree(node.children, depth + 1));