sensors: fix millis() rollover stall in GPS time-sync + minor cleanups

next_check and next_gps_update stored a future millis() value in a signed
long and compared with a naive '>'. After the ~24.8-day millis() sign flip
the deadline sits above the wrapped millis(), so the block never runs again
and GPS->RTC time-sync (and the location cache refresh) stall permanently
until reboot. Switch to unsigned deadlines with the wrap-safe signed-
difference compare '(long)(millis() - deadline) > 0', matching the idiom in
Dispatcher::millisHasNowPassed.

Also: reorder the MicroNMEALocationProvider ctor init-list to declaration
order (silences -Wreorder) and drop the always-true 'if (_claims > 0)' guard
in claim() (claim() always runs after _claims++, so it is >= 1).

src/helpers/sensors/EnvironmentSensorManager.cpp

@@ -889,11 +889,11 @@ void EnvironmentSensorManager::stop_gps() {
 void EnvironmentSensorManager::loop() {
 
   #if ENV_INCLUDE_GPS
-  static long next_gps_update = 0;
+  static unsigned long next_gps_update = 0;
   if (gps_active) {
     _location->loop();
   }
-  if (millis() > next_gps_update) {
+  if ((long)(millis() - next_gps_update) > 0) {
 
     if(gps_active){
     #ifdef RAK_WISBLOCK_GPS

src/helpers/sensors/MicroNMEALocationProvider.h

@@ -42,14 +42,14 @@ class MicroNMEALocationProvider : public LocationProvider {
     int8_t _claims = 0;
     int _pin_reset;
     int _pin_en;
-    long next_check = 0;
+    unsigned long next_check = 0;
     long time_valid = 0;
     unsigned long _last_time_sync = 0;
     static const unsigned long TIME_SYNC_INTERVAL = 1800000; // Re-sync every 30 minutes
 
 public :
     MicroNMEALocationProvider(Stream& ser, mesh::RTCClock* clock = NULL, int pin_reset = GPS_RESET, int pin_en = GPS_EN,RefCountedDigitalPin* peripher_power=NULL) :
-    _gps_serial(&ser), nmea(_nmeaBuffer, sizeof(_nmeaBuffer)), _pin_reset(pin_reset), _pin_en(pin_en), _clock(clock), _peripher_power(peripher_power) {
+    nmea(_nmeaBuffer, sizeof(_nmeaBuffer)), _clock(clock), _gps_serial(&ser), _peripher_power(peripher_power), _pin_reset(pin_reset), _pin_en(pin_en) {
         if (_pin_reset != -1) {
             pinMode(_pin_reset, OUTPUT);
             digitalWrite(_pin_reset, GPS_RESET_FORCE);
@@ -62,9 +62,7 @@ public :
 
     void claim() {
         _claims++;
-        if (_claims > 0) {
-            if (_peripher_power) _peripher_power->claim();
-        }
+        if (_peripher_power) _peripher_power->claim();
     }
 
     void release() {
@@ -143,7 +141,7 @@ public :
 
         if (!isValid()) time_valid = 0;
 
-        if (millis() > next_check) {
+        if ((long)(millis() - next_check) > 0) {
             next_check = millis() + 1000;
             // Re-enable time sync periodically when GPS has valid fix
             if (!_time_sync_needed && _clock != NULL && (millis() - _last_time_sync) > TIME_SYNC_INTERVAL) {