Second pass after the cache/arch fix unblocked `pnpm build` and surfaced
later-stage failures:
- Desktop packaging called `pnpm --filter @fusion/desktop dist:mac -- <args>`,
but pnpm leaks the `--` separator into the script args. electron-builder
stops parsing at `--`, so `--publish never` was ignored — it auto-published
to api.github.com/repos/gsxdsm/fusion/releases and 404'd. The same leak
dropped Linux's `--x64 --arm64`. Switch all four desktop packaging steps to
`pnpm --filter @fusion/desktop exec electron-builder ...`, which forwards
args cleanly (verified locally).
- Windows CLI signing now skips when WINDOWS_CERTIFICATE_BASE64 is absent,
mirroring the macOS guard (was hard-failing the bun-windows-x64 job).
- Desktop build spawns workspace .cmd bins with shell:true on Windows; Node
rejects .cmd/.bat spawns without a shell (EINVAL) since CVE-2024-27980,
which broke `@fusion/desktop build` on the Windows runner.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>