Add staggered transmit-only channel text beacons

src/helpers/BeaconFeatureConfig.h

@@ -0,0 +1,12 @@
+#pragma once
+
+// Fixed STM32 images retain their existing features and filesystem boundary.
+// Host tests explicitly opt in when exercising the beacon implementation.
+#ifndef MESH_ENABLE_TX_BEACONS
+  #if !defined(STM32_PLATFORM) && (defined(ESP32_PLATFORM) \
+      || defined(NRF52_PLATFORM) || defined(RP2040_PLATFORM))
+    #define MESH_ENABLE_TX_BEACONS 1
+  #else
+    #define MESH_ENABLE_TX_BEACONS 0
+  #endif
+#endif