State Streaming Setup - Copilotkit

<Steps> <Step> ### Stream partial state updates while Claude responds

For streaming state, parse the agent's structured deltas as they arrive and
emit CopilotKit state updates before the final message is complete. This
branch runs inside the streamed tool-argument handler.

<DemoCode file="src/agents/agent.py" region="state-streaming-delta-emission" />

</Step> </Steps>