Fix file upload timeout and UX issues

- Increase Dio receiveTimeout from 10s to 60s to allow file uploads and org creation
  to complete (Nextcloud user provisioning takes 5-7s)
- Hide 'Empty Folder' text and back button in root directory (main folder)
- Back button and empty message now only show in actual subdirectories

b0esche_cloud/lib/pages/file_explorer.dart

@@ -798,6 +798,10 @@ class _FileExplorerState extends State<FileExplorer> {
                       return const SizedBox.shrink();
                     },
                   ),
+                  // Only show back button and "Empty Folder" text if not at root
+                  if (state.currentPath != '/')
+                    Column(
+                      children: [
                         const SizedBox(height: 16),
                         Row(
                           children: [
@@ -826,6 +830,8 @@ class _FileExplorerState extends State<FileExplorer> {
                         ),
                       ],
                     ),
+                ],
+              ),
             );
           }
 

b0esche_cloud/lib/services/api_client.dart

@@ -13,7 +13,7 @@ class ApiClient {
       BaseOptions(
         baseUrl: baseUrl,
         connectTimeout: const Duration(seconds: 10),
-        receiveTimeout: const Duration(seconds: 10),
+        receiveTimeout: const Duration(seconds: 60), // Increased for file uploads and org operations
       ),
     );