Rename noctalia-shell to noctalia and add support

* Rename `nooctalia-plugins` to `noctalia-plugins` in host modules and
  plugin definitions
* Update Hyprland keybindings and exec-once to use the new `noctalia`
  commands
* Add `stylixImage` option and enable pointer cursor in
  `modules/core/user.nix`
* Introduce `modules/home/nixpkgs.nix` to allow unfree packages and
  insecure Electron
* Add full Noctalia configuration module with settings for audio,
  bar, calendar, location, notifications, plugins, shell, wallpaper,
  and widgets
* Enable `noctalia` in `modules/home/stylix.nix` and replace legacy
  `noctalia-shell` imports in `modules/home/default.nix`

modules/home/default.nix

@@ -7,7 +7,8 @@ _: {
     ./hyprland
     ./kitty
     ./librewolf
-    ./noctalia-shell
+    ./noctalia
+    # ./noctalia-shell
     ./obsidian
     ./scripts
     ./vscodium
@@ -27,6 +28,7 @@ _: {
     ./lutris.nix
     ./mangohud.nix
     ./nextcloud.nix
+    ./nixpkgs.nix
     ./obs-studio.nix
     ./ollama.nix
     ./onlyoffice.nix