Add DFU to BLE Stack

src/helpers/nrf52/SerialBLEInterface.cpp

@@ -177,6 +177,11 @@ void SerialBLEInterface::begin(const char* prefix, char* name, uint32_t pin_code
 
   Bluefruit.setEventCallback(onBLEEvent);
 
+  // Register DFU on the main BLE stack so paired clients can discover it
+  // without switching the device into a separate OTA-only BLE mode first.
+  bledfu.setPermission(SECMODE_ENC_WITH_MITM, SECMODE_ENC_WITH_MITM);
+  bledfu.begin();
+
   bleuart.setPermission(SECMODE_ENC_WITH_MITM, SECMODE_ENC_WITH_MITM);
   bleuart.begin();
   bleuart.setRxCallback(onBleUartRX);

src/helpers/nrf52/SerialBLEInterface.h

@@ -8,6 +8,7 @@
 #endif
 
 class SerialBLEInterface : public BaseSerialInterface {
+  BLEDfu bledfu;
   BLEUart bleuart;
   bool _isEnabled;
   bool _isDeviceConnected;