feat(presets): MESH_ENABLE_RADIO_PRESETS build switch (off on STM32 and ESP-NOW-only)

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

examples/simple_sensor/SensorMesh.cpp

@@ -650,8 +650,10 @@ uint8_t SensorMesh::handleLoginReq(const mesh::Identity& sender, const uint8_t*
   getRNG()->random(&reply_data[8], 4);   // random blob to help packet-hash uniqueness
   reply_data[12] = FIRMWARE_VER_LEVEL;
 
+#if MESH_ENABLE_RADIO_PRESETS
   // A fresh strict-admin login keeps a remotely loaded radio preset.
   if (client->isAdmin()) _cli.radioPresets().onAdminLogin();
+#endif
   return 13;  // reply length
 }