Add open-source issue recommender domain

[jasanpe]

Implements a distinct open-source issue recommendation domain for aolabsai/ao_pyth#9.

Summary:

• Adds a local 12-item issue catalog covering frontend, backend, docs, testing, devops, data, and CLI work.
• Keeps the AO-compatible 8-bit input shape with area, effort, beginner-friendly, and contributor-goal bits.
• Adds a CLI and Streamlit entrypoint for ranking issues from contributor preferences and liked/disliked issue feedback.
• Adds focused unittest coverage for encoding, ranking, feedback-driven reranking, and validation errors.

Verification:

• python -m unittest discover -s tests -p "test_open_source_issue_domain.py"
• python -m unittest discover -s tests
• python -m py_compile open_source_issue_domain.py open_source_issue_recommender.py arch__OpenSourceIssueRecommender.py
• python open_source_issue_recommender.py --area frontend --effort small --level new --beginner-friendly --goal portfolio --stack react --stack css --limit 3