feat: 159 tests passing — conversation memory complete

feat: clickable PubMed links for cited PMIDs

fix: RAG prompt JSON format restored — PMIDs working

refactor: centralize system prompts in prompts.py

docs: Plan 4 complete — all 4 plans done

feat(generation): enterprise RAG pipeline — verified working with Claude + Pinecone

chore: initialise enterprise folder structure Alz-Bot