Fix: ToolNode에 미정의 변수 tools 대신 self._base_tools 사용

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/agent/agent_service.py

@@ -218,7 +218,7 @@ class AgentService:
         builder = StateGraph(MessagesState)
         builder.add_node("agent", call_model)
         builder.add_node("query_rewrite", query_rewrite_node)
-        builder.add_node("tools", ToolNode(tools))
+        builder.add_node("tools", ToolNode(self._base_tools))
         builder.add_edge(START, "agent")
         builder.add_conditional_edges("agent", route_after_agent)
         builder.add_edge("query_rewrite", "tools")