Forgejo returns 200 with HTML content-type on successful merge instead
of JSON. Our API helper threw on resp.json(), causing merge to report
failure even though the PR merged. Now treats non-JSON 200 as success.
This was causing PRs #732 and #789 to show as conflict in our DB while
actually merged on Forgejo, and tripping the merge circuit breaker.
Pentagon-Agent: Leo <294C3CA1-0205-4668-82FA-B984D54F48AD>