Desired model (`claude-3.5-sonnet`) not pre-selected when using link

Hello!

First off, neat idea for a project! 🎉

I made the following URL just to quickly test this: https://github.com/copilot?model=claude-3.5-sonnet&prompt=hey%20there!%20let's%20build%20something%20awesome.

The model that is selected is `GPT-5.2`, which is not what is specified in the URL (`claude-3.5-sonnet`).

Reproduce the behavior with the reported URL and inspect the link-handling entry point that reads the model parameter. Done means a URL specifying claude-3.5-sonnet opens with that model pre-selected instead of GPT-5.2.

Scritto dal modello di indicizzazione a partire dal testo della issue.