bakery already fully covers what the PKGBUILD provided (binary, dependency
declarations) except a LICENSE copy, which bakery.toml's new license_file
field now closes. Removes packaging/arch/ and .forgejo/workflows/package.yml;
adds the LICENSE artifact to each release/dev-release/beta-release
workflow's prepare step. Not pacman-installed inside BOS today (BOS already
consumes these apps exclusively via build-local.sh's skel-staging), so this
only removes the option to `pacman -S` outside of BOS/bakery.
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.
