feat(hardening): declare hardening module using 'nix-mineral'

hosts/andromache/default.nix

@@ -56,6 +56,7 @@ in
   desktop.ly.enable = true;
   docker.enable = true;
   k8s.enable = true;
+  hardening.enable = true;
   hcloud.enable = true;
   networking = {
     enable = true;

hosts/astyanax/default.nix

@@ -40,6 +40,7 @@ in
       model = "arc-140t";
     };
   };
+  hardening.enable = true;
   keyboard.enable = true;
   localization.enable = true;
   memory = {

hosts/hecuba/default.nix

@@ -24,6 +24,7 @@ in
   hardware.facter.reportPath = ./facter.json;
 
   docker.enable = true;
+  hardening.enable = true;
   secrets.enable = true;
   ssh.enable = true;
   tailscale.enable = true;