fix(system): enhance system stability, watchdog, and safe shutdown

- Increase F9PSerialReadTask stack size to 8192 to prevent stack overflows
- Add timeout to BluetoothSerial flush() to avoid infinite blocking loops
- Implement Task Watchdog Timer (TWDT) for F9PSerialReadTask for auto-recovery
- Add power-fail interrupt handling via GPIO 27 to safely close SD card logs
- Enable hardware reset reason logging to SD card on startup

lib/BluetoothSerial/BluetoothSerial.cpp

@@ -30,7 +30,8 @@ const char * _spp_server_name = "ESP32SPP";
 //#define RX_QUEUE_SIZE 512 //Original
 //#define TX_QUEUE_SIZE 32
 
-#define SPP_TX_QUEUE_TIMEOUT 1000
+// #define SPP_TX_QUEUE_TIMEOUT 1000
+#define SPP_TX_QUEUE_TIMEOUT 10
 #define SPP_TX_DONE_TIMEOUT 1000
 #define SPP_CONGESTED_TIMEOUT 1000
 
@@ -763,8 +764,10 @@ size_t BluetoothSerial::write(const uint8_t *buffer, size_t size)
 void BluetoothSerial::flush()
 {
     if (_spp_tx_queue != NULL){
-        while(uxQueueMessagesWaiting(_spp_tx_queue) > 0){
+        int timeout = 20;
+        while(uxQueueMessagesWaiting(_spp_tx_queue) > 0 && timeout > 0){
            delay(100);
+           timeout--;
         }
     }
 }