The GitLab reference pattern required "gitlab" in the hostname and
https, so a pasted merge request URL from a host like
code.example.com or an http-only internal instance parsed to null and
the checkout dialog and branch picker ignored it. The /-/merge_requests/
path is already GitLab's own, so match it on any host, the way the
Forgejo pattern does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>