refactor(app): App-per-screen navigation, remove menu_level entirely

Splits the ad-hoc menu_level state machine into standalone Apps with a
uniform parent/child exit convention (long-press CONFIRM -> parent):
clock_app renamed to home_app (boot-default), new set_clock_app
extracted from home_app's time-edit mode, new ipc_bind_app extracted
from menu_app's old level-2 screen, and the sensor-type selection step
merged into pair_app as its new initial state. menu_app now only holds
the 4-item top-level list (language toggle inline). Also makes both
menu_app and pair_app's up/down navigation cyclic (wraps at both ends).

App/app_ipc_bind.c

@@ -0,0 +1,85 @@
+#include "app_manager.h"
+#include "xtell.h"
+#include "ui.h"
+#include "rgb.h"
+#include "event.h"
+#include "system.h"
+#include "../Drivers/rf.h"
+
+// 外部引用的全局系统状态变量
+extern SystemState current_state;
+extern volatile u16 ms_tick;
+
+// 本应用私有变量
+static u16 last_bind_tx_ms = 0; // 记录上一次绑定发射的时间戳
+
+// 声明本应用的生命周期回调函数
+static void IpcBindApp_OnStart(void);
+static void IpcBindApp_onRun(void);
+static void IpcBindApp_onClose(void);
+static EventResult IpcBindApp_onEvent(SystemEvent *evt);
+
+// 实体化定义摄像头一键绑定应用控制块 (从 menu_app 的"LIAISON"选项进入)
+WristbandApp ipc_bind_app = {
+    APP_ID_IPC_BIND,
+    "IpcBind",
+    IpcBindApp_OnStart,
+    IpcBindApp_onRun,
+    IpcBindApp_onClose,
+    IpcBindApp_onEvent
+};
+
+/**
+ * @brief IpcBindApp 启动回调
+ */
+static void IpcBindApp_OnStart(void)
+{
+    last_bind_tx_ms = ms_tick;       // 记录初始发射时间
+    current_state = STATE_IPC_BIND;  // 系统设为 IPC 绑定状态
+    UI_ShowBindingPage(CLONED_ADDR); // 绘制相机绑定信息页
+    XTELL_LOG("[IpcBindApp] Started\r\n");
+}
+
+/**
+ * @brief IpcBindApp 轮询主回调
+ */
+static void IpcBindApp_onRun(void)
+{
+    // ====== 控制青色双灯珠同步呼吸效果 (呼吸周期 1000ms) ======
+    u16 breath = ms_tick % 1000;
+    u8 val = (breath < 500) ? (breath * 2 / 5) : ((1000 - breath) * 2 / 5); // 亮度映射 0~200
+    RGB_Send(0, val, val, 0, val, val); // 渲染青色 (G+B)
+
+    // ====== 控制无线发射，每 500ms 广播一次配对数据 ======
+    if (ms_tick - last_bind_tx_ms >= 500 || ms_tick < last_bind_tx_ms)
+    {
+        last_bind_tx_ms = ms_tick; // 备份当前时间戳
+        RF_SetMode(2);             // 暂时切换射频芯片为发射调制模式
+        EV1527_Transmit(CLONED_ADDR, 0x01); // 调制发射手环克隆 ID + 绑定数据码 0x01
+        RF_SetMode(0);             // 切回关闭状态，避免产生噪声
+        XTELL_LOG("[IpcBindApp] Binding frame emitted\r\n");
+    }
+}
+
+/**
+ * @brief IpcBindApp 退出清理回调
+ */
+static void IpcBindApp_onClose(void)
+{
+    RGB_Send(0, 0, 0, 0, 0, 0); // 熄灭 RGB
+    XTELL_LOG("[IpcBindApp] Closed\r\n");
+}
+
+/**
+ * @brief IpcBindApp 接收按键事件处理回调
+ */
+static EventResult IpcBindApp_onEvent(SystemEvent *evt)
+{
+    // 长按 ■ 确认键，取消绑定，退出发射并返回主菜单 (父 App)
+    if (evt->key_event == KEY_EVENT_CONFIRM_LONG) {
+        current_state = STATE_PAIR_MENU;
+        AppManager_SwitchToForeground(&menu_app);
+        return EVENT_HANDLED;
+    }
+    return EVENT_IGNORED;
+}