Ubuntu 26.10 (Stonking Stingray) is stable, so it can be named as a build base instead of falling back to the `devel` wildcard. The build base has to match the release of the system that builds the image, so hosts on 26.10 had no valid build base other than `devel`. Also adds a 26.10 spread system, and uses `qemu-user-binfmt` on 26.04 and later, where `qemu-user-static` is no longer packaged. --- - [ ] I've followed the [contribution guidelines](https://github.com/canonical/imagecraft/blob/main/CONTRIBUTING.md). - [ ] I've signed the [CLA](http://www.ubuntu.com/legal/contributors/). - [ ] I've successfully run `make lint && make test`. - [ ] I've added or updated any relevant documentation. - [ ] In documents I changed, I [added a meta description](https://canonical-starflow.readthedocs-hosted.com/how-to/add-a-page-meta-description/) if one was missing. - [ ] I've updated the relevant release notes.