Adding initial support for LLM Customisation

[sanveer-osahan]

This pull request introduces support for custom language models (LLMs) by replacing the model_api_key parameter with a more flexible model_client_options parameter. It also updates the documentation, configuration, initialization logic, and tests to reflect this enhancement.

Core Changes for Custom LLM Support:

• Configuration Updates:

  • Replaced model_api_key with model_client_options in the StagehandConfig class, allowing users to specify multiple options such as apiKey and baseUrl for custom LLMs. (stagehand/config.py, [1] [2]

• Initialization Logic:

  • Updated the initialization logic in stagehand/main.py to handle model_client_options and extract apiKey from it, falling back to the MODEL_API_KEY environment variable if necessary. (stagehand/main.py, stagehand/main.pyL71-R74)
  • Removed redundant logic for populating model_client_options dynamically. (stagehand/main.py, stagehand/main.pyL92-L96)

• LLM Client Enhancements:

  • Modified stagehand/llm/client.py to support baseURL in addition to api_base for custom LLM configurations. (stagehand/llm/client.py, stagehand/llm/client.pyL57-R57)

Documentation Updates:

• README.md:
  • Added a new section on LLM customization, including an example of how to configure StagehandConfig with model_client_options for a custom LLM. (README.md, README.mdR163-R178)

Test Coverage:

• Unit Tests:
  • Updated existing tests to replace model_api_key with model_client_options. (tests/unit/llm/test_llm_integration.py, [1]; tests/unit/test_client_api.py, [2]; tests/unit/test_client_initialization.py, [3]
  • Added new tests to validate custom LLM configurations, including overrides and environment variable fallbacks. (tests/unit/test_client_initialization.py, tests/unit/test_client_initialization.pyR206-R234)

request changes

[miguelg719]

let's address the comments, I made a branch contrib/132 that you can set as the target to merge to (to run full CI)