Examples and agent templates: guardrail so initialize_runtime() is not invoked per request

[u2135]

Summary

“Vibe coding” with examples may lead to calling initialize_runtime() in the wrong lifecycle scope.

Acceptance criteria

• Audit examples/ (e.g. OpenAI Agents README) and any starter templates: init once at app/agent worker startup.
• Add a short “Performance pitfalls” subsection: per-request init, per-intercept preprocess.

References

• examples/openai_agents/README.md (and related entrypoints)