The review_requested case was reading e.RequestedReviewer (singular *GiteaUser),
but in some Gitea versions/webhook payloads this field is nil while the
reviewer data comes in requested_reviewers (plural array).
Now uses event.Reviewers from normalizePREvent, which handles both
PullRequest.RequestedReviewers and top-level requested_reviewers.
Keeps e.RequestedReviewer as a fallback for older Gitea versions.
JimKarvo