Uses GitHub's atomic stack merge for the active stack or a stack or pull request
number. Every pull request through the selected target merges together, or none
of them merge.
Usage:
```bash
The merge method is required. Quinjet passes confirmation to `gh stack` only
after its own `--yes` is present.
```bash
quinjet stack merge 42 --squash --yes
```
See [`quinjet stack`](./README.md) for lifecycle safety and prerequisites.