Add BioMistral LLM

[QuiteRocks]

Adds a second LLM option using BioMistral (trained on PubMed scientific papers)

What it does:

• New file: scr/llm/biomistral_llm.py
• Same structure as local_llm.py but uses BioMistral Model
  -Inculdes few shot examples and pydantic valiadation