https://github.com/meshcore-dev/MeshCore/issues/989 - persist GPS enabled state to preferences

Add GPS configuration to NodePrefs structure and persist the GPS
enabled state when toggled via UI. This ensures GPS settings are
retained across device restarts.

examples/companion_radio/MyMesh.cpp

@@ -739,6 +739,8 @@ MyMesh::MyMesh(mesh::Radio &radio, mesh::RNG &rng, mesh::RTCClock &rtc, SimpleMe
   _prefs.bw = LORA_BW;
   _prefs.cr = LORA_CR;
   _prefs.tx_power_dbm = LORA_TX_POWER;
+  _prefs.gps_enabled = 0;       // GPS disabled by default
+  _prefs.gps_interval = 0;      // No automatic GPS updates by default
   //_prefs.rx_delay_base = 10.0f;  enable once new algo fixed
 }
 
@@ -776,6 +778,7 @@ void MyMesh::begin(bool has_display) {
   _prefs.sf = constrain(_prefs.sf, 5, 12);
   _prefs.cr = constrain(_prefs.cr, 5, 8);
   _prefs.tx_power_dbm = constrain(_prefs.tx_power_dbm, 1, MAX_LORA_TX_POWER);
+  _prefs.gps_enabled = constrain(_prefs.gps_enabled, 0, 1);  // Ensure boolean 0 or 1
 
 #ifdef BLE_PIN_CODE // 123456 by default
   if (_prefs.ble_pin == 0) {
@@ -803,6 +806,10 @@ void MyMesh::begin(bool has_display) {
 
   radio_set_params(_prefs.freq, _prefs.bw, _prefs.sf, _prefs.cr);
   radio_set_tx_power(_prefs.tx_power_dbm);
+
+#if ENV_INCLUDE_GPS == 1
+  sensors.setSettingValue("gps", _prefs.gps_enabled ? "1" : "0");
+#endif
 }
 
 const char *MyMesh::getNodeName() {