Added MCU temp sensor to the companion

Fixes #2896

examples/companion_radio/MyMesh.cpp

@@ -657,6 +657,11 @@ uint8_t MyMesh::onContactRequest(const ContactInfo &contact, uint32_t sender_tim
       // query other sensors -- target specific
       sensors.querySensors(permissions, telemetry);
 
+      float temperature = board.getMCUTemperature();
+      if(!isnan(temperature)) { // Supported boards with built-in temperature sensor. ESP32-C3 may return NAN
+        telemetry.addTemperature(TELEM_CHANNEL_SELF, temperature); // Built-in MCU Temperature
+      }
+
       memcpy(reply, &sender_timestamp,
              4); // reflect sender_timestamp back in response packet (kind of like a 'tag')
 
@@ -1640,6 +1645,11 @@ void MyMesh::handleCmdFrame(size_t len) {
   } else if (cmd_frame[0] == CMD_SEND_TELEMETRY_REQ && len == 4) {  // 'self' telemetry request
     telemetry.reset();
     telemetry.addVoltage(TELEM_CHANNEL_SELF, (float)board.getBattMilliVolts() / 1000.0f);
+    float temperature = board.getMCUTemperature();
+    if(!isnan(temperature)) { // Supported boards with built-in temperature sensor. ESP32-C3 may return NAN
+      telemetry.addTemperature(TELEM_CHANNEL_SELF, temperature); // Built-in MCU Temperature
+    }
+
     // query other sensors -- target specific
     sensors.querySensors(0xFF, telemetry);