test(docs): validate reviewer route contract

[stacknil]

Summary

• add a no-dependency reviewer route contract validator for root and SBOM reviewer docs
• add CI coverage for reviewer-route drift across root docs, supporting project boundaries, and SBOM examples
• link the validator from the root README and reviewer brief

Validation

• python scripts\\validate-reviewer-routes.py
• python -m py_compile scripts\\validate-reviewer-routes.py
• git diff --cached --check
• changed-file privacy/sensitive-pattern scan: no matches for local paths, institution identifiers, credentials, or secret-like terms

Notes

PR #68 is still open but stale; I did not merge it because its branch predates later project additions and would remove current weather-toolkit files if applied as-is.