Update flake.lock, disable affinity, add SSH host

Refresh flake.lock with newer revisions for several packages, turn off
the
Affinity suite in the desktop configuration, and add a new SSH host
entry
for gitssh.garandplg.com with its own identity and port settings.

hosts/Garand-Desktop/system-modules.nix

@@ -34,7 +34,7 @@ _: {
   /*
   Media & Graphics
   */
-  affinity.enable = true; # Affinity: professional graphics suite
+  affinity.enable = false; # Affinity: professional graphics suite
 
   packages = {
     /*