Reorganize desktop roles: extract common bootstrap and host-specific layers

- Add profile_desktop_common with shared desktop bootstrap (emptty, PAM,
  dotfiles, templates, GPG, Maildir, Flatpak, st, external tools)
- Add profile_desktop_host with host-specific tasks (NVIDIA/PRIME on nymph)
- Reduce profile_desktop_i3 to i3/X11-only tasks
- Create profile_desktop_hyprland for Hyprland Wayland session
- Add dual-session support (i3 + Hyprland) on nymph with session choice
- Create shared Hyprland/Waybar dotfiles under dotfiles/desktop/
- Fix Waybar: bottom position, no persistent workspaces, sort by number
- Rename host_dotfiles to host_i3_dotfiles for clarity
- Make emptty restart manual by default to avoid session drops

ansible/inventory/host_vars/ikaros.yml

@@ -1,6 +1,12 @@
 ---
 hostname: ikaros
 
+desktop_sessions_enabled:
+  - i3
+
+desktop_default_session: i3
+desktop_default_session_env: xorg
+
 host_packages:
   - mesa-dri
   - vulkan-loader
@@ -8,7 +14,7 @@ host_packages:
   - mesa-vaapi
   - xf86-video-amdgpu
 
-host_dotfiles:
+host_i3_dotfiles:
   - src: .config/autorandr/
     dest: .config/autorandr/
     mode: preserve