Add pet adoption recommender domain

[dennywu2966]

/claim #9

This adds a distinct pet adoption recommender domain for the AO Labs paid bounty: aolabsai/ao_pyth#9

What changed:

• Added a local adoptable pet catalog covering dogs, cats, rabbits, birds, and small mammals.
• Added AO-compatible 8-bit input encoding with the existing arch_i = [3, 2, 1, 2] shape: species, energy, child-friendly fit, and adopter goal.
• Added deterministic fallback ranking for household context and feedback-driven ordering so reviewers can run it without private AO packages.
• Added a CLI and optional Streamlit demo plus focused unit tests.
• Documented the domain demo in the README.

Validation run locally:

• python3 -m unittest discover -s tests
• python3 -m py_compile pet_adoption_domain.py pet_adoption_recommender.py arch__PetAdoptionRecommender.py tests/test_pet_adoption_domain.py
• python3 pet_adoption_recommender.py --species dog --home house --activity high --children --experience experienced --goal active --limit 3
• git diff --check

If accepted for the paid bounty, preferred payout is PayPal: https://paypal.me/ZuodongWu?locale.x=en_US&country.x=US

Transparency: AI-assisted with Codex; I reviewed the diff and validation output before submitting.