Add Zsh to the list of available shells in the Darwin services module.
Introduce new Nix configurations for aarch64-darwin, including system packages and font settings.
Set up user-specific environment for Harald on aarch64-darwin system.
This commit renames the 'fonts' array in the darwin system fonts module to 'packages'. The refactor is aimed at improving the code readability and making the name more descriptive and representative of its content.
