Foundation: project scaffolding and Python package skeleton #61

Goal

Give the repository a working Python project so every later issue has somewhere to put code and a way to test it.

Scope

• pyproject.toml for a package named jev_cookbook under src/, Python 3.10 or newer (the floor of typesafe-sdk).
• Core dependencies kept small: numpy, matplotlib, jupyter/nbclient for execution. Optional extras: live (typesafe-sdk), ml (scikit-learn), dev (ruff, pytest).
• ruff configured for lint and format, including notebooks. pytest configured with --import-mode=importlib so recipe folders can carry their own tests/.
• A README section or docs/development.md with the three commands a contributor needs: install, lint, test.
• A trivial test that imports the package, so CI has something to run.

Acceptance criteria

• pip install -e ".[dev]" works in a clean virtual environment on Linux and Windows
• ruff check ., ruff format --check ., and pytest all pass
• No dependency requires a network call or API key at import time
• Dependency policy (what goes in core and what goes in an extra) is written down
• Lint and tests pass in CI, or locally with the output pasted in the pull request if CI does not exist yet

Dependencies

• None. This is the first issue to pick up.
• Unblocks Foundation: CI baseline for lint, tests, and the README catalog check #62, Foundation: decision backends with typed answers, replay, and scripted modes #63, Foundation: evaluation toolkit #66, Foundation: notebook style, plotting theme, and run-mode header #67
• Tracked in Epic: Foundation #74

References

• Recipe contract
• Catalog
• TypeSafe documentation index for tools: https://docs.typesafe.ai/llms.txt
• Python SDK: https://docs.typesafe.ai/sdk/python