feat: Tier 1-3 optimisations + 4-agent audit — streaming queue, BM25 JSON, IP rate limit, async council, JSON logging, eval feedback loop, PubMed fallback, multi-worker deploy

fix: rebuild biomedical entity graph with scispaCy NER, clean bad nodes

fix: frontend import path, graph_explorer scale arg, routing test mocks

feat: eval harness, guardrails, graph explorer UI, multi-provider web search

feat: add NLI entailment checker using cross-encoder/nli-deberta-v3-small