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/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;