Bump default container OS version from Debian 12 to 13 across multiple LXC setup scripts. Refactor update_script functions for consistency, improve messaging, and standardize apt usage. Update Kimai install and update scripts to use setup_php, setup_composer, and fetch_and_deploy_gh_release helpers, and switch from MySQL to MariaDB. Update Kometa to use Python 3.13. Minor improvements to backup, cleanup, and service management steps in several scripts.
