Integrate graph with agent execution.
runAgentAt :: Graph -> UserId -> NodeId -> IO ()forkAgentAt :: Graph -> UserId -> NodeId -> IO RunId1. Set node status to Running 2. Build context from graph position 3. Run agent with context + graph tools 4. Stream ops to graph via appendOp 5. Set node status to Done/Error
Omni/Agent/Graph/Execution.hs