fix(demo): wire every showcase path end-to-end with auto-resolved artifacts

feat(researcher): DCE-MRI BBB permeability bridge + drug-dose adjuster

feat(agents): retrieve_context corpus dispatch (reference vs clinical)

feat(agents): register run_fusion tool for multi-modal disease confidence

docs(agents/tools): TODO race on shared parquet output for concurrent /agent/run

Add project files

fix(agents/tools): parameterize processed_dir + translate HTTPException → ValueError

feat(agents): Tool dataclass + registry + 4 tool wrappers (3 pipelines + RAG)