Classify the structured review writer in the native writer ledger #1977

The full test run for adoption PR #1976 failed test_every_writer_is_classified: the new governed scripts/record_review.py is a YAML writer but was not entered in the native writer ledger. The run otherwise passed 3,785 tests, with 87 skips and eight deselections.

This helper creates immutable review bundles only under reviews/structured/. Its write operations do not edit kb/communities, so recording scientific curation events for those observations would be incorrect.

Use the existing _EXEMPT report-only classification with an explicit reason. Keep the writer scanner, mandatory classification check, existing owed corpus-writer backlog, and curation-history requirements unchanged. Verify the writer-ledger and actual shared-saver contract tests, followed by normal PR CI. Do not edit the canonical helper to hide it from the scanner.