Publish and verify desktop release artifacts

## Problem

Signed platform artifacts are not yet connected to Draftgoblin’s intentional version-tag release or verified alongside its existing distribution channels.

## Proposed change

Publish macOS and Windows desktop artifacts through the tag-controlled release workflow while preserving PyPI and Homebrew TUI releases.

## Acceptance Criteria

- [ ] Desktop artifacts use the same version and intentional release tag as the Python distribution.
- [ ] Release automation publishes verified macOS and Windows downloads.
- [ ] Existing PyPI and Homebrew publication and verification continue to pass.
- [ ] Fresh-install and upgrade verification cover both desktop platforms.
- [ ] Installation, version checks, upgrade, uninstallation, and release-recovery procedures are documented.
- [ ] A failed desktop build cannot silently publish an incomplete desktop release.
- [ ] Mobile, app-store, automatic-update, and Linux-installer work remains outside this ticket.