Update to version 0.9.12:

- Add changelog entry for version 0.9.12 with detailed updates and fixes.
- Improve error reporting for failed VPN connections, unresolved gateways, and stale routes.
- Fix crash on application quit and ensure modal dialogs open in the foreground.
- Update CMake project version and changelog revision.
- Rebuild `krunner_openfortigui` for compatibility with version 0.9.12.