chore: drop redundant packages and options

- packages.nix is the baseline: drop neovim (nixvim), nvd, sof-firmware (enableAllFirmware), qtmultimedia (v4 leftover); vial moves to vial.nix, wl-clipboard to noctalia.nix, claude-code becomes a plain package here
- drop packages and options already provided elsewhere: noctalia (home-manager), gnupg/pinentry-qt (agent), gtk/qt themes, sddm Theme.Current, zsh plugins (home-manager), group = users, empty firewall lists
- single-package lists without `with pkgs;`, steam package inside its block

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

modules/nixos/noctalia.nix

@@ -1,14 +1,14 @@
-{ pkgs, inputs, ... }:
+{ pkgs, ... }:
+
 {
-  # install noctalia and helper packages
+  # helpers for the noctalia shell (the shell itself comes from home-manager)
   environment.systemPackages = with pkgs; [
-    inputs.noctalia.packages.${pkgs.stdenv.hostPlatform.system}.default
     adw-gtk3
-    adwaita-qt
     adwaita-qt6
     brightnessctl
     ddcutil
     playerctl
+    wl-clipboard
     wl-mirror
   ];
 }