feat(workers): Define WorkerState for the Researcher subgraph

backend/src/ea_chatbot/graph/workers/researcher/state.py

@@ -0,0 +1,21 @@
+from typing import TypedDict, List, Dict, Any, Optional
+from langchain_core.messages import BaseMessage
+
+class WorkerState(TypedDict):
+    """Internal state for the Researcher worker subgraph."""
+    
+    # Internal worker conversation
+    messages: List[BaseMessage]
+    
+    # The specific sub-task assigned by the Orchestrator
+    task: str
+    
+    # Search context
+    queries: List[str]
+    raw_results: List[str]
+    
+    # Number of internal retry/refinement attempts
+    iterations: int
+    
+    # The final research summary to return to the Orchestrator
+    result: Optional[str]