Adaptor — MarianMT fr->en, DGT-TM fine-tuned

MarianMT opus-mt-fr-en fine-tuned on DGT-TM-2023 for the pipeline's FR->EN normalization step.

M3 result: 55.09 -> 58.92 BLEU (+3.83) on a clean, leakage-controlled DGT-TM-2023 held-out set.