add worblehat daemons

hosts/skrot/configuration.nix

@@ -67,6 +67,27 @@
         };
       };
     };
+    deadline-daemon = {
+      enable = lib.mkEnableOption "" // {
+        description = ''
+          Whether to enable the worblehat deadline-daemon service,
+          which periodically checks for upcoming deadlines and notifies users.
+
+          Note that this service is independent of the main worblehat service,
+          and must be enabled separately.
+        '';
+      };
+
+      onCalendar = lib.mkOption {
+        type = lib.types.str;
+        description = ''
+          How often to trigger rendering the map,
+          in the format of a systemd timer onCalendar configuration.
+
+          See {manpage}`systemd.timer(5)`.
+        '';
+        default = "*-*-* 10:15:00";
+      };
   };
 
   systemd.services."serial-getty@ttyUSB0" = lib.mkIf (!config.virtualisation.isVmVariant) {