Harness Node Splitter

Split a workflow description into constrained harness nodes using the chapter's rule "nodes differ by tool surface, not by prompt." Given candidate operations each with a declared tool set, merge the ones whose tool surfaces overlap >= 80% (prompt variations of one role) and split the ones with distinct tool surfaces (different roles), then emit the per-node constrained context scope the harness enforces (tool surface + memory reads/writes + input/output contract). Implements the RedAI scanner-vs-validator distinction and the 80%-overlap Tip from Agentic Graph RAG Ch2. Use when turning a horizontal-workflow sketch into executable nodes. NOT for scheduling nodes into paral…