- Add BOOK_ROOT, QUARTO_DIR, TOOLS_DIR, DEPS_DIR, DOCKER_DIR env vars to all workflows
- Update path references to use centralized env vars
- Fix requirements.txt to reference book/tools/dependencies
- Fix pyproject.toml entry points: cli.main -> book.cli.main
- Add __init__.py to book/ and book/tools/ for Python package support
- Fix Dockerfile path casing (dockerfile -> Dockerfile)
- Fix publish-live.yml relative path after cd
This enables TinyTorch to coexist at repo root alongside book/ directory.