Langfuse agent example

Follow the Langfuse integration guide to install the SDK and set credentials. Then run an agent:

super agent run my_agent --goal 'Explain the result' --observe langfuse

Open the trace in Langfuse and inspect the agent_run observation. Nested operations appear under the same trace. DSPy model calls appear when the DSPy OpenInference instrumentor is enabled as described in the guide.