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/gnupg.nix

@@ -1,29 +1,24 @@
+# A graphical pinentry never grabs the tty, so a passphrase prompt can't take
+# over a terminal driven by a coding agent. The cache lasts a working day, and
+# an unattended signature fails after two minutes instead of blocking forever.
+
 { config, pkgs, ... }:
 
 {
-  # enable gnupg agent
   programs.gnupg.agent = {
     enable = true;
-    # a graphical pinentry never grabs the tty, so a passphrase prompt can no
-    # longer take over a terminal that a coding agent is driving
     pinentryPackage = pkgs.pinentry-qt;
     settings = {
-      # keep the key unlocked for a full working day instead of 10 minutes,
-      # so signing commits asks at most once per session
       default-cache-ttl = 86400;
       max-cache-ttl = 86400;
-      # fail an unattended signature instead of blocking on a prompt forever
       pinentry-timeout = 120;
     };
   };
 
-  environment.systemPackages = with pkgs; [
-    gnupg
-    pinentry-qt
-    # fallback for sessions without a display, switch pinentryPackage to use it
-    pinentry-curses
+  environment.systemPackages = [
+    pkgs.pinentry-curses # fallback for sessions without a display
     # prime the passphrase cache on demand, e.g. before an agent session
-    (writeShellScriptBin "gpg-unlock" ''
+    (pkgs.writeShellScriptBin "gpg-unlock" ''
       echo | ${config.programs.gnupg.package}/bin/gpg --clearsign --output /dev/null
       echo "gpg key unlocked"
     '')