feat(extraction): Batch API extractor (~50% cheaper), fix stale cost banner

feat: retrieval grounding, trial quality, and drug-name typo suggestions

feat: automate ALS seed entities from trials and paper corpus

perf(extraction): switch to Haiku + add per-paper retry for missed PMIDs

feat: Stage 4 — entity extraction + knowledge graph + KG-expanded RAG

feat: initial project scaffold and Stage 2 ingestion pipeline