Clarify that DQ-3's 'VERIFIED CLEAN' covers the ingest pipeline (txt -> chunks)
only — it treats the .txt as ground truth. The upstream PDF/source -> .txt
extraction (done outside codex-py) is unmeasured and shown to be lossy (DQ-3's
dropped chunks were garbled OCR tables already present in the .txt). Add DQ-6 to
measure that layer; 36 source PDFs are available. Note R-A/R-C (re-ingest from
PDF/.tex) would largely sidestep it.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>