Remove Arch/nymph path, restore nymph as Void desktop

Delete all Arch-specific files (packages_arch role, profile_desktop_gnome
role, arch.yml group_vars, nymph.yml host_vars, arch dotfiles). Revert
nymph to the void group in inventory, remove the arch play from site.yml,
and restore profile_desktop_host/tasks/nymph.yml to its pre-Arch state
(GRUB + NVIDIA + prime-run). Preserve Void improvements introduced
alongside Arch work (desktop_void_dotfiles, desktop_void_source_tools,
profile_desktop_i3 dir additions, void-specific conditions).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ansible/roles/services_systemd/tasks/main.yml

@@ -19,11 +19,3 @@
   loop_control:
     label: "{{ item }}"
 
-- name: Enable systemd services without starting them
-  tags: [services, packages]
-  ansible.builtin.systemd:
-    name: "{{ item }}"
-    enabled: true
-  loop: "{{ enabled_services_only | default([]) }}"
-  loop_control:
-    label: "{{ item }}"