further attic configurations

modules/servers/atticd.nix

@@ -24,6 +24,14 @@ in
             avg-size = 64 * 1024; # 64 KiB
             max-size = 256 * 1024; # 256 KiB
           };
+          compression = {
+            type = "xz";
+            level = 16;
+          };
+          garbage-collection = {
+            interval = "7 days";
+            default-retention-period = "7 days";
+          };
         };
       };
       nginx.virtualHosts."${cfg.host}" = lib.mkIf cfg.enableProxy (