Polish linked public card docs

[jang1563]

Summary

• Rewrites the linked public card docs as reader-facing guides: documentation map, system card, evaluation card, release status card, public statement guide, and portfolio brief.
• Replaces internal alpha, boundary, blocker, and provenance-control language with concise public release/status language.
• Updates README key-document labels to point readers to the public documentation map, release status, and statement guide.
• Extends public-doc consistency checks across the linked card docs.

QA

• python3 scripts/validate_public_docs_consistency.py
• python3 -m unittest tests/test_public_docs_consistency.py tests/test_release_manifest.py
• git diff --check
• make release-qa
• make hpc-public-qa