Stagehand Agent mode should allow providing baseURL for OpenAICUAClient

[majkiw]

Background

Hi, when configuring Stagehand itself, you can override llmClient options, or even the whole llmClient like this:

const stagehand = new Stagehand({
  browserbaseSessionID: browserSession.sessionId,
  modelClientOptions: {
    apiKey: "",
    baseURL: "",
  },
  llmClient: CustomOpenAIClient()

💯

Problem

However when running stagehand.agent you can only set the apiKey via:

const agent = stagehand.agent({
  options: {
    apiKey: process.env.OPENAI_API_KEY,
  },

Because all the other parameters, most importantly baseURL, are ignored in the OpenAICUAClient:

    // Store client options for reference
    this.clientOptions = {
      apiKey: this.apiKey,
    };

    // Initialize the OpenAI client
    this.client = new OpenAI(this.clientOptions);

Ask

Could stagehand.agent support the whole export type ClientOptions = OpenAIClientOptions | AnthropicClientOptions; options, just like Stagehand constructor does?
At the very least, the baseURL (that nota bene seems to be passed in the AnthropicCUAClient.ts)

For bonus points: allow for a full llmClient override, just like in the Stagehand constructor to support custom instrumentation.

[majkiw]

I went ahead and created the minimal PR that respects baseURL in the OpenAICUAClient.ts (matching the AnthropicCUAClient.ts): #644