Gap: Many hypotheses lack structured evidence chains. Query: SELECT h.id, h.title FROM hypotheses h WHERE NOT EXISTS (SELECT 1 FROM evidence_chains ec WHERE ec.entity_id=h.id) LIMIT 20. For each hypothesis: create an evidence_chain record with: supporting evidence (pro), contradicting evidence (con), and net assessment. Use the hypothesis title, debate history, and paper links to structure the chain. Acceptance: 20 evidence_chains rows created with at least 2 pro and 1 con evidence entries each.