fix(bot): !temp and {temp} fall back to the chip's temperature

Same gap as the screens had: the bot reply, a typed message's {temp} and
the placeholder lists read only the sensors, so a board without one (the
L1) answered !temp with n/a while its telemetry carried a temperature.
The fallback moves to LocalSensors.h, shared by the screens, expandMsg()
and sensorPlaceholders(); the latter now takes the chip's temperature.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/LocalSensors.h

@@ -0,0 +1,22 @@
+#pragma once
+// This device's own readings, as the screens, the bot and message placeholders
+// read them.
+
+#include <math.h>
+#include <helpers/SensorManager.h>
+#include <helpers/sensors/LPPDataHelpers.h>
+
+// The sensors' readings, plus the chip's own temperature (NaN where a board has
+// none) when no sensor reads one: the telemetry reply sends it too, so a board
+// without a temperature sensor shows on screen and in {temp} what the app shows.
+inline void queryLocalSensors(SensorManager& sm, float mcu_temp, CayenneLPP& lpp) {
+  sm.querySensors(0xFF, lpp);
+  if (isnan(mcu_temp)) return;
+  LPPReader r(lpp.getBuffer(), lpp.getSize());
+  uint8_t ch, type;
+  while (r.readHeader(ch, type)) {
+    if (type == LPP_TEMPERATURE) return;
+    r.skipData(type);
+  }
+  lpp.addTemperature(TELEM_CHANNEL_SELF, mcu_temp);
+}