Fixes #869 Does both things suggested in the issue: - If the runtime dir can't be created, fall back to the home temporary directory (already the fallback on Linux when the runtime dir is under /tmp). - If the state dir itself can't be created, raise a StateServiceError that suggests setting CRAFT_STATE_DIR. I ran ruff, ty, codespell and the full test suite in a Linux container rather than `make lint && make test`. No new failures: the tests that fail there fail on main too. --- - [x] I've followed the [contribution guidelines](https://github.com/canonical/craft-application/blob/main/CONTRIBUTING.md). - [x] 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. - [x] I've updated the relevant release notes.