Add a `product.json` and set the extension gallery URL through that

``` { "extensionsGallery": { "serviceUrl": "https://marketplace.visualstudio.com/_apis/public/gallery", "itemUrl": "https://marketplace.visualstudio.com/items", "cacheUrl": "https://vscode.blob.core.windows.net/gallery/index", } } ```

https://github.com/getcursor/cursor/issues/2195

This is technically against the ToS of the extension gallery though