Hide the default channel slug from the URL structure

[chrislaai]

Currently, all channels appear in the URL path. It would be great if the storefront could be configured so that the default channel (e.g., "us") does not display a slug, resulting in a root domain URL (http://localhost:3000/). Non-default channels, such as Poland, would retain their slug (http://localhost:3000/pl/). This would improve user experience and provide cleaner URLs for the primary market.