feat(orchestrator): Implement Delegate node for task routing

backend/src/ea_chatbot/graph/nodes/delegate.py

@@ -0,0 +1,18 @@
+from ea_chatbot.graph.state import AgentState
+from ea_chatbot.utils.logging import get_logger
+
+def delegate_node(state: AgentState) -> dict:
+    """Determine which worker subgraph to call next based on the checklist."""
+    checklist = state.get("checklist", [])
+    current_step = state.get("current_step", 0)
+    logger = get_logger("orchestrator:delegate")
+    
+    if not checklist or current_step >= len(checklist):
+        logger.info("Checklist complete or empty. Routing to summarizer.")
+        return {"next_action": "summarize"}
+    
+    task_info = checklist[current_step]
+    worker = task_info.get("worker", "data_analyst")
+    
+    logger.info(f"Delegating next task to worker: {worker}")
+    return {"next_action": worker}