[shepherd70]

Summary

• preserve blank positional column names on Parquet cache hits for headerless workbook ingestion
• add optional live-source verification to canonical bundle reads
• report artifact and source verification as verified or explicitly skipped
• exercise source verification against the complex marine workbook regression

Validation

• targeted cache and artifact tests: pass
• secure real-workbook regression: 17 checks pass
• full package suite: pass; 5 expected opt-in skips
• R CMD check --no-manual: Status OK

Scope

No consumer repositories or source workbooks were modified. Multi-sheet default cache-key optimization remains deferred to v0.7.2 because it is performance-only.