The remote gen-index.sh call never had MINISIGN_SEC_KEY wired through, so a
missing/misconfigured secret silently produced an unsigned index.json that
overwrote the previously-signed one instead of failing the job — this is
why bread's dev track never appeared in dl.breadway.dev/dev/index.json
after the first dev-release.yml run despite it reporting success.
GitHub Actions self-hosted runners need per-repo registration on a
personal account; Forgejo Actions' runner already serves every repo
with zero setup. Moves release publishing there (dl.breadway.dev stays
the primary bakery target; GitHub release upload is kept as the
fallback via an explicit token, since Forgejo Actions has no ambient
GITHUB_TOKEN) and adds a mirror workflow to keep GitHub in sync
automatically.
