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/packages.nix

@@ -1,10 +1,11 @@
 { pkgs, ... }:
 
 {
-  # system packages
+  # baseline tools for every host
   environment.systemPackages = with pkgs; [
     btop
     cifs-utils
+    claude-code
     cowsay
     dnsutils
     ethtool
@@ -14,31 +15,25 @@
     imv
     iperf3
     jq
-    kdePackages.qtmultimedia
     ldns
     lm_sensors
     lsof
     mtr
-    neovim
     nfs-utils
     nh
     nix-output-monitor
     nmap
-    nvd
     p7zip
     pciutils
     socat
-    sof-firmware
     strace
     sysstat
     tree
     unzip
     usbutils
-    vial
     vim
     wget
     which
-    wl-clipboard
     xz
     zip
     zstd