fix(desktop): add the archiver, image viewer and cpufreq backend

Gaps against moonarch/packages/official.txt: zip, unzip and viewnior were
missing outright, and thunar-archive-plugin was installed without
xarchiver, which left its menu entries inert.

services.auto-cpufreq is the backend of the Quickshell CpuGov widget,
which calls 'auto-cpufreq --get-state' and 'pkexec auto-cpufreq --force';
without it the indicator has no state and the popout cannot switch.

modules/desktop.nix

@@ -308,6 +308,7 @@ in
 
     # Media
     vlc
+    viewnior
 
     # File manager stack. thunar and tumbler come from their modules above;
     # ffmpegthumbnailer is what tumbler uses for video thumbnails.
@@ -315,6 +316,11 @@ in
     udisks2
     ntfs3g
     ffmpegthumbnailer
+    # Backend for thunar-archive-plugin above; without it its menu entries do
+    # nothing.
+    xarchiver
+    zip
+    unzip
 
     # Theming. Same derivations the greeter uses, see flake.nix.
     moonarchThemes.gtk

modules/services.nix

@@ -20,6 +20,7 @@
   services.upower.enable = true;
   services.gvfs.enable = true;
   services.fwupd.enable = true;
+  services.auto-cpufreq.enable = true;
 
   # --- Firewall, replaces the ufw calls in post-install.sh ---
   networking.firewall.enable = true;