feat: consolidate llm service providers to only need 1 api key to use cursor-tools

[luyandadhlamini2]

Release of cursor-tools version 0.5.0 means 3 separate api keys are now needed to make best use of cursor-tools.
These are:
Gemini for thinking & repo compression tasks.
Perplexity for search
Anthropic / OpenAI for stagehand browser control

I suggest that:

1. A suitably capable llm service provider is chosen for core functionality in cursor-tools.
2. The number of api keys required is consolidated to as few as possible (ideally just 1).

This will make tool adoption for new users a lot easier.

[eastlondoner]

Yes!

I am evaluating OpenRouter and ModelBox for this.

I’ve found that these providers do not always give the same behaviour as the original APIs so I will thoroughly test them first