feat: Introduce FoldersManager and useFolderData to manage and display folder contents, including documents and subfolders.

frontend/src/documents/data/useDocumentsWorkspace.ts

@@ -40,6 +40,7 @@ import { useStatusToast, type ToastVariant } from '../../lib/context/StatusToast
 import useAuthManager from './useAuthManager';
 import useTenantManager from './useTenantManager';
 import useDocuments from './useDocuments';
+import FoldersManager from '../FoldersManager';
 import { fetchDocument } from '../../lib/api/apiClient';
 import useFolderTree from '../features/folders/useFolderTree';
 import useFolderTreeActions from '../features/folders/useFolderTreeActions';
@@ -315,6 +316,12 @@ const useDocumentsWorkspace = ({
     fetchDocumentById,
   });
 
+  const foldersManagerRef = useRef<FoldersManager | null>(null);
+  if (!foldersManagerRef.current) {
+    foldersManagerRef.current = new FoldersManager();
+  }
+  const foldersManager = foldersManagerRef.current;
+
   const documentLookup = useSyncExternalStore(
     (onStoreChange) => documentsManager.subscribe(onStoreChange),
     () => documentsManager.getSnapshot(),
@@ -1301,6 +1308,8 @@ const useDocumentsWorkspace = ({
     uploadQueue,
     clearUploadQueue,
     documentsFilter,
+    documentsManager,
+    foldersManager,
   };
 
   // hook callers handle rendering / routing