fix(xfce): skip Linux XFCE/XRDP desktop stack on macOS

The all-in-one flow reached "Update apt cache" in the
xfce_desktop_minimal_runtime role on macOS and failed with
`[Errno 2] No such file or directory: b'update'` (no apt on Darwin).

XFCE + XRDP is a Linux remote-desktop stack and is meaningless on macOS,
which already has a native GUI. Guard both role includes in
setup-xfce-xrdp.yaml with `ansible_os_family != 'Darwin'` so the apt/systemd
tasks never run there. Linux behavior is unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

setup-xfce-xrdp.yaml

@@ -9,9 +9,13 @@
   vars:
     xworkspace_console_enable_xrdp: false
   tasks:
+    # XFCE/XRDP is a Linux remote-desktop stack (apt-based, systemd) and is not
+    # applicable to macOS, which already has a native GUI. Skip the whole stack
+    # on Darwin so the apt-driven tasks never run there.
     - name: Include XFCE desktop runtime role
       ansible.builtin.include_role:
         name: roles/vhosts/xfce_desktop_minimal_runtime
+      when: ansible_os_family != 'Darwin'
 
     - name: Include XRDP server role when enabled
       ansible.builtin.include_role:
@@ -23,4 +27,6 @@
         xfce_user_groups:
           - sudo
           - docker
-      when: xworkspace_console_enable_xrdp | bool
+      when:
+        - ansible_os_family != 'Darwin'
+        - xworkspace_console_enable_xrdp | bool