Add pre-commit hook for ruff and black

[travisjneuman]

Description

Add a pre-commit configuration so contributors automatically get their Python code checked by ruff and formatted by black before committing.

Acceptance Criteria

• Add .pre-commit-config.yaml to the repo root
• Configure ruff and black hooks
• Add setup instructions to CONTRIBUTING.md
• Test that the hooks run correctly on a sample commit

[travisjneuman]

Resolved in 36dceb1: Added .pre-commit-config.yaml with ruff lint and format hooks. Updated CONTRIBUTING.md with setup instructions.