This PR is an alternative to #699 which enables unwrapping a huma.Context back into its router-specific request/response object or router-specific context, effectively escaping Huma and giving back full control to the user. It's generally recommended to not do this, but there are legitimate use-cases where this could be handy to have as an option. Example:

router := http.NewServeMux()
api := humago.New(router, huma.DefaultConfig("My API", "1.0.0"))

api.UseMiddleware(func(ctx huma.Context, next func(huma.Context)) {
	r, w := humago.Unwrap(ctx)
	fmt.Println("Request started", r.Method, r.URL)
	w.Header().Set("X-Request-Start", time.Now().Format(time.RFC3339))
	next(ctx)
})

This implementation does not modify any interfaces in Huma itself, nor does it require manually casting any or things like that. Each adapter simply provides a convenience Unwrap() function that returns the underlying data.

This should also make it fairly simple to switch routers as you can find/replace the router-specific package (e.g. humachi → humago) and things will just work or provide a compile-time error if the return types changed, making it easy to fix, instead of waiting for a runtime error.