[feat] add daemon support with automatic restart on crash

src/app/daemon.h

@@ -0,0 +1,44 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2025-11-19
+ * Copyright (c) 2025 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _DAEMON_H_
+#define _DAEMON_H_
+
+#include <functional>
+#include <string>
+
+// default restart delay (milliseconds)
+#define DAEMON_DEFAULT_RESTART_DELAY_MS 1000
+
+class Daemon {
+ public:
+  using MainLoopFunc = std::function<void()>;
+
+  Daemon(const std::string& name);
+
+  // start daemon (restart after 1 second by default)
+  bool start(MainLoopFunc loop);
+
+  // request exit
+  void stop();
+
+  // check if running
+  bool isRunning() const;
+
+ private:
+  std::string name_;
+  bool runWithRestart(MainLoopFunc loop);
+
+#ifdef _WIN32
+  bool running_;
+#else
+  static Daemon* instance_;
+  void runUnix(MainLoopFunc loop);
+  volatile bool running_;
+#endif
+};
+
+#endif