services-artix and postcfg Calamares modules don't exist in upstream
Calamares (they're Garuda/Artix fork patches). Our custom Calamares
builds from pure upstream, so these steps get silently skipped during
installation, leaving NO services enabled in the installed system.
Replace them with shellprocess@enable-services, which uses the
built-in shellprocess module to run a post-install script that:
- Detects the init system (dinit/openrc/runit/s6)
- Enables all system services via boot.d symlinks or equivalent
- Sets up user services (pipewire, wireplumber) for the created user
Affects both online and offline installer settings.