Add chat UX improvements: message actions toolbar (copy/delete/regenerate)
on hover, inline explainability subgraph visualization from RAG/agent
queries, and token metadata for all chat modes. Enhance graph page with
SPO query filters, configurable triple limit, and type legend overlay.
Extract shared graph utilities for reuse across components.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
