Feature Request: Gitea / Forgejo OAuth2 & embedded links support

Hi,

I'd like to request native support for Gitea and its fork Forgejo in two areas:

1. OAuth2 login provider


Allow using a self-hosted Gitea/Forgejo instance as an OAuth2 identity provider, similar to the existing GitHub/GitLab support. This is especially valuable for self-hosted teams that don't want to rely on third-party providers (Google, Slack, etc.).

Gitea/Forgejo follows standard OAuth2 flows with a configurable base URL, so implementation should be straightforward.

2. Embedded links (unfurl)


Similar to how Outline already handles GitHub and GitLab links, it would be great to have rich embed/unfurl support for Gitea/Forgejo links — repositories, issues, pull requests, commits, etc.

Thanks for considering this!