If the Gitea release already exists for a tag (e.g. from a retried
workflow), fall back to fetching the existing release ID instead of
failing with KeyError.
- Add build-dist-linux.sh: venv-based tarball with systemd installer
- Add build-linux job to release.yml (parallel with build-windows)
- Include Linux download in release body
- Allow pytest to pass when no tests are collected (exit code 5)
alexei.dolgolyov