refactor(event): replace global 60s inactivity timer with per-second tick event

Adds KEY_EVENT_SECOND_TICK, generated once per real second from
Clock_IncMS() via a new second_tick_flag and pushed through the normal
event queue, so every foreground App's onEvent() receives it and
decides independently whether to act. Removes the old global
inactivity_timer (60s sleep from anywhere) entirely. HomeApp now
accumulates its own idle-second counter and sleeps after 10s idle
specifically while on the home screen; MenuApp's existing 10s
auto-close is converted from onRun() polling to the same tick+reset
pattern for consistency. Any non-tick key event resets each app's own
counter to 0.

App/clock.h

@@ -8,6 +8,7 @@ extern u8 current_hour;
 extern u8 current_min;
 extern u8 current_sec;
 extern volatile u8 clock_updated;
+extern volatile bit second_tick_flag; // 整秒滴答标志位，每次 current_sec 递增时置 1，供主循环转换为事件
 
 /**
  * @brief 系统软时钟毫秒递增更新 (在 1ms 中断中调用)