feat: enhance accessibility and testing with data-test attributes and improve error handling

apps/web/app/[locale]/home/[account]/site-builder/[pageId]/edit/page.tsx

@@ -20,7 +20,7 @@ export default async function EditPageRoute({ params }: Props) {
 
   const api = createSiteBuilderApi(client);
   const page = await api.getPage(pageId);
-  if (!page) return <div>Seite nicht gefunden</div>;
+  if (!page) return <AccountNotFound />;
 
   return (
     <SiteEditor

apps/web/app/[locale]/home/[account]/site-builder/page.tsx

@@ -69,7 +69,7 @@ export default async function SiteBuilderDashboard({ params }: Props) {
             )}
           </div>
           <Link href={`/home/${account}/site-builder/new`}>
-            <Button>
+            <Button data-test="site-new-page-btn">
               <Plus className="mr-2 h-4 w-4" />
               Neue Seite
             </Button>

apps/web/app/[locale]/home/[account]/site-builder/posts/page.tsx

@@ -38,7 +38,7 @@ export default async function PostsManagerPage({ params }: Props) {
     >
       <div className="space-y-6">
         <div className="flex justify-end">
-          <Button>
+          <Button data-test="site-new-post-btn">
             <Plus className="mr-2 h-4 w-4" />
             Neuer Beitrag
           </Button>