Trigger is workflow_dispatch exclusively so builds happen only when
explicitly requested from the Actions UI, not on every branch push.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Mirrors build-app.yml's three-platform matrix (Linux/macOS/Windows)
but uploads the bundles as workflow artifacts instead of creating
Gitea releases or syncing to GitHub, so feature branches can be
smoke-tested without cluttering the release streams.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>