- Added one internal generic builder covering the repeated apiKey/baseUrl
resolution, bundled reference map, providerId and fetchDynamicModels closure.
- Migrated openai, cerebras, novita, aimlApi, alibabaCodingPlan, venice,
baseten and moonshot, and routed createSimpleOpenAICompletionsOptions
through it; deleted the duplicate responses-side helper.
- Preserved fetchDynamicModels key PRESENCE per site, since the apiKey spread
guard omits the key entirely rather than setting it undefined.