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/steam.nix

@@ -1,20 +1,13 @@
 { pkgs, ... }:
 
 {
-  # enable steam and open firewall
   programs.steam = {
     enable = true;
+    # fix black screen when running under xwayland-satellite
+    package = pkgs.steam.override { extraArgs = "-system-composer"; };
     remotePlay.openFirewall = true;
     dedicatedServer.openFirewall = true;
     localNetworkGameTransfers.openFirewall = true;
-    # add proton-glorious-eggroll
-    extraCompatPackages = with pkgs; [
-      proton-ge-bin
-    ];
-  };
-
-  # fix black screen in steam when using xwayland-satellite
-  programs.steam.package = pkgs.steam.override {
-    extraArgs = "-system-composer";
+    extraCompatPackages = [ pkgs.proton-ge-bin ];
   };
 }