[codex] Productize distribution and demo packaging

[yangfei222666-9]

Summary

• Add release-published support to the existing PyPI trusted-publishing workflow.
• Add a bounded Streamlit / Hugging Face Space demo source under demo/huggingface_space/.
• Productize the README with PyPI badges, install/demo/quickstart/architecture/roadmap/contribution sections.
• Include demo files in the source distribution and extend compile gates to cover demo/.
• Fix benchmark checkout execution and stale startup-recovery timestamps.
• Add tests for benchmark execution and demo packaging.
• Include TaijiOS ops-check artifacts for scope, staging, and closeout evidence.

Verification

• .venv/bin/pre-commit run --all-files passed.
• python3 -m pytest -q passed with 69 passed.
• python3 -m compileall -q self_improving_loop examples benchmarks demo tests passed.
• build + twine check passed for wheel and sdist.
• git diff --cached --check passed before commit.
• summary.json and event_flow.jsonl parsed successfully.

Boundaries

This PR does not publish a release, upload to PyPI, create a Hugging Face Space, tag, or merge itself. PyPI publish and public demo deployment remain separate manual gates.