fix(voice) reject ignored explicit-client options - #4527

Summary

Reject organization and project when OpenAIVoiceModelProvider receives an explicit openai_client.

An explicit AsyncOpenAI client already owns its organization and project settings. The voice provider currently rejects api_key and base_url in this configuration but silently accepts and ignores organization and project because those values are only stored when the provider constructs its own client.

This aligns the voice provider with the same explicit-client contract already used by OpenAIProvider.

Reproduction

client = AsyncOpenAI(api_key="test")
provider = OpenAIVoiceModelProvider(
    openai_client=client,
    organization="org_other",
)

On current main, construction succeeds but organization="org_other" has no effect. The provider continues using the organization configured on client.

Test plan

Extends the existing explicit-client conflict regression test to cover both organization and project while preserving the valid client-only path.

Issue number

N/A