Sentence Transformers training: migrate from SentenceTransformer.fit to SentenceTransformerTrainer

AI Impact Summary

The provided guide is outdated and describes SentenceTransformer.fit (pre-v3.0), which has been superseded by SentenceTransformerTrainer. Production pipelines relying on the old API must migrate to the new training workflow to avoid deprecated patterns and ensure compatibility with Hugging Face Hub models like all-MiniLM-L6-v2 and distilroberta-base. Expect necessary changes to dataset formatting, loss function selection, and model packaging, with downstream impacts on CI pipelines and model registry artifacts if not migrated.