Directory structure from getDirectoryStructure()
Regex pattern to split files (default: 2+ newlines). Must have 'g' flag.
OptionalmaxTokensPerChunk: numberOptional maximum tokens per chunk (will split if exceeded)
Characters per token estimate (default: 2.5 for code)
New hierarchical structure with chunks added to file nodes
Chunks all files in a directory structure tree. Returns a new tree with chunks added to all file nodes (immutable).