feat: scatter 31 handcrafted items across 4 modules → 3,031 total items

feat: backfill 37 handcrafted items to reach exactly 3,000 items and update paper

fix: dataset integrity - pruned 67 malformed items

fix: shuffle MCQ candidates, fix length bias, add difficulty tracking

fix: removed all duplicate candidates across the benchmark using rigorous multi-pass review

feat: release v1.0 (1,200 handcrafted items, 16 modules, 0% contamination)