MAGIC value for powerReason should be stored in RTC backup on Horus (#7096)

- Allows the radio main application to start correctly when coming from an app in RAM
- Refactoring of the `UNEXPECTED_SHUTDOWN()` process
- Saves the RTC battery as BACKUP RAM is not needed on normal shutdown
- On PWR OFF on an ALERT, the radio won't show the next alert before shutting down
- Bootloader flashable through the SD Manager

radio/src/switches.cpp

@@ -561,8 +561,7 @@ void checkSwitches()
   bool refresh = false;
 #endif
 
-  while (1) {
-
+  while (true) {
 #if defined(PCBTARANIS) || defined(PCBHORUS)
   #define GETADC_COUNT 1
 #endif
@@ -749,6 +748,8 @@ void checkSwitches()
 #if defined(PWR_BUTTON_PRESS)
     uint32_t power = pwrCheck();
     if (power == e_power_off) {
+      drawSleepBitmap();
+      boardOff();
       break;
     }
     else if (power == e_power_press) {
@@ -767,7 +768,7 @@ void checkSwitches()
 
     doLoopCommonActions();
 
-    wdt_reset();
+    WDG_RESET();
 
     RTOS_WAIT_MS(10);
   }