docs: clarify compiler and runtime positioning

[abrichr]

Summary

• state the compiler and governed runtime in direct language
• explain deterministic healthy replay and governed repair
• keep the evidence and qualification limits

This PR contains only the intended README positioning change. PR #381 gained
an unrelated production-admission commit during its checks, so this branch was
created from the current origin/main and contains only the copy commit.

Validation

• uv run python scripts/check_release_consistency.py
• uv run pytest -q tests/test_consistency.py (22 passed)
• git diff --check

[abrichr]

Closing this duplicate in favor of #381. #381 contains the same positioning change plus the required admission-driven product-state contract. The source branch remains available.