Dotfiles for my macos setup

:truck: move chezmoi setup scripts to .chezmoiscripts directory master

- Move `run_once_install_packages.sh.tmpl`, `run_once_settings.sh.tmpl`, `run_onchange_install-sandbox-deps.sh.tmpl`, `run_onchange_set-default-apps.sh.tmpl` to `.chezmoiscripts/` - Update README and AGENTS.md links to reflect new script paths - Reorganize AGENTS.md with clearer structure and instructions