PDF import batch: all 5 imported and validated

All five PDFs are now imported and validated. Economics, Accounting, and Property Theory #7ESDBJ source #8C28Q3) and Algebraic Models for Accounting Systems #NBH3BE source #F6P4LS) were resumed from the preserved Datalab outputs in runs #Z2YATG and #BEVDM5 after fixing Quadlog large-transaction performance, atomic PDF metadata writes, and retry idempotence. Seven orphan graphs created by timed-out Economics retries were removed after backup. Search and embeddings were rebuilt successfully with zero embedding errors. The three earlier imports remain #WYH36B #67REFX and #AULNWD