add firmware source code (#4)

* add firmware source code

firmware/main/apps/app_ai_agent/app_ai_agent.cpp

@@ -0,0 +1,52 @@
+/*
+ * SPDX-FileCopyrightText: 2026 M5Stack Technology CO LTD
+ *
+ * SPDX-License-Identifier: MIT
+ */
+#include "app_ai_agent.h"
+#include <hal/hal.h>
+#include <mooncake.h>
+#include <mooncake_log.h>
+#include <assets/assets.h>
+#include <smooth_lvgl.hpp>
+
+using namespace mooncake;
+using namespace smooth_ui_toolkit::lvgl_cpp;
+
+AppAiAgent::AppAiAgent()
+{
+    // Configure App name
+    setAppInfo().name = "AI.AGENT";
+    // Configure App icon
+    setAppInfo().icon = (void*)&icon_ai_agent;
+    // Configure App theme color
+    static uint32_t theme_color = 0x33CC99;
+    setAppInfo().userData       = (void*)&theme_color;
+}
+
+// Called when the App is installed
+void AppAiAgent::onCreate()
+{
+    mclog::tagInfo(getAppInfo().name, "on create");
+}
+
+// Called when the App is opened
+// You can construct UI, initialize operations, etc. here
+void AppAiAgent::onOpen()
+{
+    mclog::tagInfo(getAppInfo().name, "on open");
+
+    GetHAL().startXiaozhi();
+}
+
+// Called repeatedly while the App is running
+void AppAiAgent::onRunning()
+{
+}
+
+// Called when the App is closed
+// You can destroy UI, release resources, etc. here
+void AppAiAgent::onClose()
+{
+    mclog::tagInfo(getAppInfo().name, "on close");
+}