feat(bootstrap): add desktop environment support with configurable DE, DM, and display target

roles/configuration/vars/main.yml

@@ -65,3 +65,15 @@ configuration_platform_config:
     grub_mkconfig_prefix: grub-mkconfig
     locale_gen: false
     init_system: runit
+
+# Display manager auto-detection from desktop environment name.
+configuration_desktop_dm_map:
+  gnome: gdm
+  kde: sddm
+  xfce: lightdm
+  sway: greetd
+  hyprland: ly@tty2
+  cinnamon: lightdm
+  mate: lightdm
+  lxqt: sddm
+  budgie: gdm