add configurable GPS update interval

Make GPS update interval configurable via settings instead of using hardcoded 1 second value. The interval is persisted from preferences and can be adjusted at runtime through the sensor manager settings interface

src/helpers/sensors/EnvironmentSensorManager.h

@@ -25,6 +25,7 @@ protected:
 
   bool gps_detected = false;
   bool gps_active = false;
+  uint32_t gps_update_interval_ms = 1000;  // Default 1 second
 
   #if ENV_INCLUDE_GPS
   LocationProvider* _location;