Context

Create project-level documentation for development workflow, including CLAUDE.md for AI-assisted development context.

Acceptance Criteria

• CLAUDE.md with project context, conventions, build/test commands
• CONTRIBUTING.md with development setup, branching strategy, commit conventions
• docs/getting_started.md with setup instructions
• README.md updated with setup instructions and project status

Dependencies

• Initialize project structure with pyproject.toml and src layout #20 (project structure must exist)