Add xdg settings, cache, cleanup script

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/eirene/base/default.nix

@@ -11,7 +11,6 @@
   networking.hostName = "eirene";
 
   # https://github.com/NixOS/nixos-hardware/tree/master/lenovo/legion/16achg6
-
   hardware = {
     cpu.amd.updateMicrocode = true;
 

hosts/eirene/format.nix

@@ -58,6 +58,10 @@
                     mountpoint = "/nix";
                     mountOptions = ["subvol=nix" "compress=zstd" "noatime"];
                   };
+                  "/cache" = {
+                    mountpoint = "/cache";
+                    mountOptions = ["subvol=cache" "compress=zstd" "noatime"];
+                  };
                 };
               };
             };