pub fn create_directory_tree(depth: usize, file_name: &str) -> Result<TempDir> {
            let dir = tempdir()?;
            let mut current = dir.path().to_path_buf();

            for i in 0..depth {
                current = current.join(format!("level{i}"));
                fs::create_dir(&current)?;
                File::create(current.join(file_name))?.write_all(b"test")?;
            }
            Ok(dir)
        }
Creates a directory structure with specified depth and a test file
in each directory Returns a TempDir with nested directories
up to depth
crates/forge_walker/src/walker.rs