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/core/user.nix

@@ -11,6 +11,7 @@
   keyboardLayout,
   gitEmail,
   location,
+  stylixImage,
   ...
 }: {
   imports = [inputs.home-manager.nixosModules.home-manager];
@@ -31,6 +32,7 @@
         gitEmail
         gitUsername
         location
+        stylixImage
         ;
     };
     users.${username} = {
@@ -43,6 +45,7 @@
         username = "${username}";
         homeDirectory = "/home/${username}";
         stateVersion = "25.11";
+        pointerCursor.enable = true;
         shell.enableFishIntegration =
           if shell == "fish"
           then true