main
fix: mypy type annotations in chat.py, health.py, graph.py (S6.1.3)
fix: unify streaming/non-streaming behavior, model routing, user identification, ACL metadata
fix: zero mypy errors across proxy/app/ (S6.1.3)
fix: mypy type annotations in slm_trainer.py and migrations.py (S6.1.3)
feat: complete implementation across all teams — DDD, AI/ML, Data, SRE, QA/Security
fix: proxy RAG pipeline, graph building in streaming, config defaults
fix: type-ignore on OTLPSpanExporter=None assignment (S6.1.3)
RAG System Init