Update Agentic python sdk with universal endpoint

[dhruvj07]

Update the Langraph and CrewAI agents' code to utilize the unified endpoint provided by the Javelin SDK

[safayavatsal]

Already using the universal endpoint; remaining work is the rebrand

Both notebooks already follow the universal-endpoint pattern via register_openai:

• examples/agents/crewai_highflame.ipynb — javelin_client.register_openai(openai_client, route_name="openai_univ")
• examples/agents/langgraph_highflame.ipynb — client.register_openai(openai_client, route_name="openai_univ")

That's exactly what this issue asked for. The remaining gap is that both notebooks still reference the v1 SDK (from javelin_sdk import JavelinClient, JavelinConfig, JAVELIN_API_KEY, javelin_api_key=) — pre-rebrand. That rebrand sweep is already tracked by #242 ("Update examples and documentation to use the updated highflame sdk and cli references"), which covers all examples, not just these two.

Closing as a strict subset of #242. The agentic notebooks will get updated as part of that sweep.