Restricted citation projection example

The adjacent generated staging tree proves that a synthetic restricted_source record can export allowlisted citation metadata while excluding its raw body. export-manifest.json contains output and transformation digests but no source path or private input digest.

Validate with:

python researcher/scripts/validate_export.py check \
  --staging-dir researcher/exports/examples/restricted-citation-v1

The example source is intentionally synthetic and committed under researcher/fixtures/export/; real restricted bodies do not belong in this repository.