Chandra 2 OCR: SOTA open-source 85.9% olmOCR benchmark

4B parameters (vs 9B en v1), 85.9% olmOCR benchmark. Tables 89.9%, math 89.3%, headers 92.5%. Multilingual 72.7% avg (90 idiomas) vs Gemini 2.5 Flash 60.8%. Marzo 2026