Incorrect copilot custom models in vscode

- Copilot Chat Extension Version:
- VS Code Version: 1.128.0-insider (bff8736385420572b86b407d6ba73bb97961166f)
- OS Version: Darwin arm64 25.5.0
- Feature (e.g. agent/edit/ask mode): model selection
- Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet): none

Steps to Reproduce:

1. Create Organization on GitHub
2. Set up custom models with OpenRouter (`https://github.com/organizations//settings/copilot/custom-models`)
3. Open VSCode and open Copilot Models panel
4. See all custom models to have 98k context windows regardless of the configuration

5. Check Chat Debug View confirm that Chat received the context windows length, but didn't use