Function isFolder

isFolder(item: FileSystemItem): item is FolderEntry
Type guard to check if an item is a folder.
Parameters
- item: FileSystemItem
Returns item is FolderEntry
Example
```
if (isFolder(item)) {
  // item is FolderEntry
  console.log('Folder path:', item.path);
} else {
  // item is FileEntry
  console.log('File ID:', item.fileId);
}
```
- Defined in file-manager/types.ts:179