[P] ibu-boost: a GBDT library where splits are *absolutely* rejected, not just relatively ranked[P]

I built a small gradient-boosted tree library based on the screening transform from "Screening Is Enough" (Nakanishi 2026, arXi:2604.01178). The paper was originally written for Transformers, but the core idea - replacing relative comparison with absolute-threshold rejection - maps naturally onto GBDT split selection. Disclaimer: I'm not affiliated with the paper's author. This is an independent implementation that applies the screening idea to GBDTs. The idea in one paragraph Every GBDT implementation picks the split with the highest gain among all candidates.