refactor: change to litterate config

Configuration is now held by the `.org` files. All `.nix` files are
tangled from the org-mode files.

modules/desktop/gnome.org

@@ -0,0 +1,51 @@
+#+title: GNOME
+#+setupfile: ../headers
+
+* GNOME
+GNOME is my desktop environment of choice on the hosts that don’t run
+a bare Wayland compositor like Hyprland or Sway on their own. I keep
+it around in case I break my config in either compositor. Here’s the
+skeleton of the =nixos.gnome= module.
+#+begin_src nix :tangle yes
+{config, ...}: let
+  m = config.flake.modules.nixos;
+in {
+  flake.modules.nixos.gnome = {...}: {
+    imports = [m.xserver];
+
+    <<display-manager>>
+    <<gnome-extras>>
+  };
+}
+#+end_src
+
+GNOME still needs the keyboard layout and video driver settings from
+[[file:xserver.org][xserver]], so this module pulls that one in directly rather than making
+every host import both.
+
+** Login and Session
+GDM is GNOME’s own display manager, paired here with the GNOME session
+itself.
+#+name: display-manager
+#+begin_src nix
+config.services.displayManager.gdm.enable = true;
+config.services.desktopManager.gnome.enable = true;
+#+end_src
+
+** Extra GNOME Services
+=gnome-browser-connector= lets browser extensions talk to the GNOME
+Shell’s own extension, =gnome-remote-desktop= gives me built-in RDP
+support, =gnome-online-accounts= handles signing into things like
+Nextcloud from GNOME’s own settings, and =sushi= is the quick file
+previewer Nautilus uses. =games= I turn off explicitly, since I have no
+use for GNOME’s bundled casual games.
+#+name: gnome-extras
+#+begin_src nix
+config.services.gnome = {
+  gnome-browser-connector.enable = true;
+  games.enable = false;
+  gnome-remote-desktop.enable = true;
+  gnome-online-accounts.enable = true;
+  sushi.enable = true;
+};
+#+end_src