Add Portkey AI as a tracing provider (#785)

This PR adds Portkey AI as a tracing provider. Portkey helps you take
your OpenAI agents from prototype to production.

Portkey turns your experimental OpenAI Agents into production-ready
systems by providing:

- Complete observability of every agent step, tool use, and interaction
- Built-in reliability with fallbacks, retries, and load balancing
- Cost tracking and optimization to manage your AI spend
- Access to 1600+ LLMs through a single integration
- Guardrails to keep agent behavior safe and compliant
- Version-controlled prompts for consistent agent performance


Towards #786

docs/ja/tracing.md

@@ -119,4 +119,5 @@ async def main():
 -   [Comet Opik](https://www.comet.com/docs/opik/tracing/integrations/openai_agents)
 -   [Langfuse](https://langfuse.com/docs/integrations/openaiagentssdk/openai-agents)
 -   [Langtrace](https://docs.langtrace.ai/supported-integrations/llm-frameworks/openai-agents-sdk)
--   [Okahu‑Monocle](https://github.com/monocle2ai/monocle)
+-   [Okahu‑Monocle](https://github.com/monocle2ai/monocle)
+-   [Portkey AI](https://portkey.ai/docs/integrations/agents/openai-agents)

docs/tracing.md

@@ -116,3 +116,4 @@ To customize this default setup, to send traces to alternative or additional bac
 -   [Langtrace](https://docs.langtrace.ai/supported-integrations/llm-frameworks/openai-agents-sdk)
 -   [Okahu-Monocle](https://github.com/monocle2ai/monocle)
 -   [Galileo](https://v2docs.galileo.ai/integrations/openai-agent-integration#openai-agent-integration)
+-   [Portkey AI](https://portkey.ai/docs/integrations/agents/openai-agents)