fix(inference): use non-empty placeholder apiKey for internal OpenAI client

[u9g]

Summary

• inference.LLM constructs an OpenAI client with apiKey: '' as a placeholder, then overwrites client.apiKey with a fresh access token before each request (see LLMStream.run).
• openai@6.36.0 tightened its credential check to reject empty-string apiKey at construction, so the constructor now throws before the per-request token is ever assigned.
• Use a non-empty 'placeholder' string instead — the value is replaced before any actual HTTP call, so behavior is unchanged on every supported openai version.

Verified by linking @livekit/agents from livekit-examples/agent-starter-node against openai@6.36.0 and removing the workaround pnpm.overrides.openai: <6.36.0; the test suite passes.

[changeset-bot]

🦋 Changeset detected

Latest commit: e2d49be

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 29 packages

Name	Type
@livekit/agents	Patch
@livekit/agents-plugin-anam	Patch
@livekit/agents-plugin-assemblyai	Patch
@livekit/agents-plugin-baseten	Patch
@livekit/agents-plugin-bey	Patch
@livekit/agents-plugin-cartesia	Patch
@livekit/agents-plugin-cerebras	Patch
@livekit/agents-plugin-deepgram	Patch
@livekit/agents-plugin-elevenlabs	Patch
@livekit/agents-plugin-google	Patch
@livekit/agents-plugin-hedra	Patch
@livekit/agents-plugin-inworld	Patch
@livekit/agents-plugin-lemonslice	Patch
@livekit/agents-plugin-liveavatar	Patch
@livekit/agents-plugin-livekit	Patch
@livekit/agents-plugin-minimax	Patch
@livekit/agents-plugin-mistral	Patch
@livekit/agents-plugin-mistralai	Patch
@livekit/agents-plugin-neuphonic	Patch
@livekit/agents-plugin-openai	Patch
@livekit/agents-plugin-phonic	Patch
@livekit/agents-plugin-resemble	Patch
@livekit/agents-plugin-rime	Patch
@livekit/agents-plugin-runway	Patch
@livekit/agents-plugin-sarvam	Patch
@livekit/agents-plugin-silero	Patch
@livekit/agents-plugins-test	Patch
@livekit/agents-plugin-trugen	Patch
@livekit/agents-plugin-xai	Patch

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.