- mathpix.py + figures.py: wrap fitz page-loop in try/finally so
doc.close() is guaranteed even on exception (no file-handle leak)
- ingest.py: DELETE FROM formulas/figures WHERE paper_id before re-insert
so --rich re-ingest is idempotent (BIGSERIAL has no natural UNIQUE key;
ON CONFLICT DO NOTHING was a no-op)
Gate: 158 passed, ruff clean, mypy clean
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>