refactor: 修复潜在bug、补全许可声明、添加类型注解、同步文档

systemd_notifier.rb

@@ -35,17 +35,20 @@ class SystemdNotifier
     MethodExecutor.record("debug", "heartbeat", "Heartbeat socket opened")
   end
 
+  # @return [Boolean]
   def enabled?
     @enable_heartbeat
   end
 
+  # @param message [String]
+  # @return [void]
   def self.notify(message)
     return unless @enable_heartbeat
     begin
       @socket.send(message, 0)
       MethodExecutor.record("debug", "heartbeat", "Heartbeat sent: #{message}")
     rescue => e
-      MethodExecutor.error("heartbeat", "Failed to send heartbeat: #{e}")
+      MethodExecutor.record("error", "heartbeat", "Failed to send heartbeat: #{e}")
       @enable_heartbeat = false
     end
   end