desktop: rename gnome.nix → desktop.nix; switch to nemo

- Rename settings/gnome.nix to settings/desktop.nix (file no longer
  has anything to do with GNOME)
- Replace nautilus with nemo — starts fast, has a hamburger menu,
  no Tracker3/Mutter D-Bus dependencies
- Exclude thunar (pulled in by XFCE) via environment.xfce.excludePackages
- Remove nautilus Tracker dconf workaround (no longer needed)
- Update $mod+E keybind and common.nix import accordingly

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

settings/gnome.nix

@@ -1,70 +0,0 @@
-# settings/gnome.nix — display manager, lightweight fallback session, GTK/Qt theming
-{ config, pkgs, lib, inputs, ... }:
-{
-  config = lib.mkIf (lib.elem config.networking.hostName [ "FredOS-Gaming" "FredOS-Macbook" ]) {
-    services.xserver.enable = true;
-    services.displayManager.ly.enable = true;
-    services.displayManager.defaultSession = "hyprland";
-    boot.plymouth.enable = false;
-
-    services.displayManager.ly.settings = {
-      animation = "gameoflife";
-      bigclock   = true;
-    };
-
-    # Lightweight fallback session — if Hyprland fails after an update,
-    # ly will list XFCE as an alternative without pulling in GNOME's
-    # keyring, tracker, or other heavyweight background services.
-    services.xserver.desktopManager.xfce.enable = true;
-
-    # Flatpak for ad-hoc app installs via Bazaar
-    services.flatpak.enable = true;
-
-    environment.systemPackages = with pkgs; [
-      nautilus             # file manager — works standalone without a GNOME DE
-      adwaita-icon-theme
-      gnome-themes-extra
-      adwaita-icon-theme-legacy
-      papirus-icon-theme
-    ];
-
-    # Cursor theme — stylix.cursor in settings/stylix.nix owns the choice.
-    environment.sessionVariables = {
-      XCURSOR_THEME = "Bibata-Modern-Ice";
-      XCURSOR_SIZE = "24";
-      XCURSOR_PATH = lib.mkForce [
-        "${pkgs.bibata-cursors}/share/icons"
-        "$HOME/.icons"
-        "$HOME/.local/share/icons"
-      ];
-    };
-
-    programs.xwayland.enable = true;
-    programs.dconf.enable = true;
-
-    home-manager.users.fred = { config, lib, pkgs, ... }: {
-      # Stylix's qt target only supports qtct; disable it to silence the warning.
-      stylix.targets.qt.enable = false;
-      # Minimal titlebars — stylix manages the GTK theme; we layer our
-      # headerbar shrink on top via stylix.targets.gtk.extraCss.
-      gtk.enable = true;
-      # Disable Tracker search — Nautilus tries to connect to the Tracker3
-      # D-Bus service at startup for recursive search. Outside GNOME the
-      # service isn't running, causing a multi-second D-Bus timeout on launch.
-      dconf.settings."org/gnome/nautilus/preferences".recursive-search = "never";
-
-      stylix.targets.gtk.extraCss = ''
-        headerbar { min-height: 0; padding: 0; margin: 0; }
-        headerbar .title { font-size: 0; }
-        window:backdrop {
-          background-color: @window_bg_color;
-          color: @window_fg_color;
-        }
-        window:backdrop headerbar {
-          background-color: @headerbar_bg_color;
-          color: @headerbar_fg_color;
-        }
-      '';
-    };
-  };
-}