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/system.c

@@ -443,9 +443,6 @@ void Wakeup_Restore(void)
     // 6. 延时 200ms 等待液晶稳压板上电稳定后，重新对 LCD 寄存器初始化
     Delay_ms(200);
     LCD_Init();
-
-    // 7. 充零闲置计时器
-    inactivity_timer = 0;
 }
 
 /**