Backport #25690 by @sebastian-sauer
gitea allows to create empty PRs.
Currently when you need approvals for a merge, you have to manually add
/files to the url to get to the files tab to approve / reject the PR.
This PR allows to open the files tab via the normal tab / link and then
fixes the layout of the files tab.
**Screenshots:**
Before:

After:

Co-authored-by: sebastian-sauer <sauer.sebastian@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>