Backport #25639 by @lunny Fix #25257 Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Addition to #22256 The `convert` package relies heavily on different models which is [disallowed by our definition of modules](https://github.com/go-gitea/gitea/blob/main/CONTRIBUTING.md#design-guideline). This helps to prevent possible import cycles. Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>