actions@gitea was never a verified email on any Gitea account, so the
CI docs-regen commit (git commit && git push, done client-side in the
runner) could never show as verified regardless of server-side
[repository.signing] config -- Gitea only signs commits it generates
itself (merge button, web editor, wiki), never ones a client pushes.
Import a dedicated passphrase-less key for a new fishconfig-bot
account (verified email, no login) from the CI_GPG_PRIVATE_KEY repo
secret and sign with it instead.