Modularize main.c into rgb, event, database, ui, system, and app_manager modules

App/app_manager.h

@@ -0,0 +1,16 @@
+#ifndef __APP_MANAGER_H__
+#define __APP_MANAGER_H__
+
+#include "config.h"
+
+// AppManager 核心接口
+void AppManager_Init(void);
+void AppManager_StartApp(AppID app_id);
+void AppManager_DispatchEvent(SystemEvent evt);
+void AppManager_RunActiveApp(void);
+AppID AppManager_GetActiveAppID(void);
+
+// 时间编辑状态机接口 (由 MenuApp 触发)
+void Start_Time_Edit(void);
+
+#endif