Pass Gitea API token to requests

This allows to display repos that aren't fully public. Some users seem
to be very interested in not having their pages viewable, and it might
make even sense to avoid e.g. search engines to read them.
If set to some random user string, this could allow to set the
visibility at least to limited (so only logged users see the repo), and
should allow to view private repos in the future with another API token.

main.go

@@ -39,6 +39,8 @@ var MainDomainSuffix = []byte("." + envOr("PAGES_DOMAIN", "codeberg.page"))
 // GiteaRoot specifies the root URL of the Gitea instance, without a trailing slash.
 var GiteaRoot = []byte(envOr("GITEA_ROOT", "https://codeberg.org"))
 
+var GiteaApiToken = []byte(envOr("GITEA_API_TOKEN", ""))
+
 //go:embed 404.html
 var NotFoundPage []byte