* update selfhst icon-URLs to use @master path
Changed all icon URLs in JSON files from 'cdn.jsdelivr.net/gh/selfhst/icons/webp/' to 'cdn.jsdelivr.net/gh/selfhst/icons@master/webp/' for consistency and to ensure the latest icons are referenced.
* added missing icons
Updated blocky.sh to improve update logic, including backup and restore of config, service management, and release fetching. Refactored blocky-install.sh to use fetch_and_deploy_gh_release for installation, removing manual release handling. Set Blocky as updateable in blocky.json.
