core/proposal_review/safety.py: dry_check INDEPENDENTLY verifies (without trusting the emitter) that every artifact is inert — status==proposal_only, mounted==false, requires_review==true, content-address consistent (filename == sha256(family:problem_text_sha256)), path under the sink, no malformed (unverifiable) file — and that no serving-path module reads the sink. Any failure is a violation.
__main__.py: python -m core.proposal_review [comprehension-failures] [--json] [--root] — read-only report + dry-check; exit 0 iff safe. Mutates nothing. 8 tests, each safety assertion proven meaningful-fail; serving-unconsumed verified on the real tree.
