How do you write modular code, implement basic error handling, and provide clear README files for a prototype?
Implement validate_prototype(files), where files is a list of dictionaries containing path and content. Return a list of validation error strings in deterministic order. Require a non-empty root README.md with ## Setup, ## Usage, and ## Errors sections; Python modules must be under src/, have non-empty content, and use unique paths.
def validate_prototype(files):