docs: record v0.5.0 closure evidence

[brownjuly2003-code]

Summary

• record verified v0.5.0 release, package/image provenance, and runtime CI samples
• mark completed external gates without claiming full project closure
• record the stale Hugging Face Space as the remaining mandatory sync-or-decommission gate

Verification

• uv run pytest -q tests/test_docs_as_code.py tests/test_docs_defaults.py tests/test_release_preflight.py --basetemp .tmp/pytest-post-release-docs-green (42 passed)
• uv run ruff check .
• uv run black --check .
• uv run pre-commit run --all-files
• git diff --check
• LF-only byte check for both edited files

Grok adversarial scoped-diff verdict: SAFE (local_grok_cli, grok-4.5-build).