Add option for automatic zerohop adverts on posision change.

lib/services/app_settings_service.dart

@@ -13,6 +13,14 @@ class AppSettingsService extends ChangeNotifier {
 
   AppSettings get settings => _settings;
 
+  int resolvedGpsIntervalSeconds(Map<String, String>? deviceCustomVars) {
+    final deviceValue = int.tryParse(deviceCustomVars?['gps_interval'] ?? '');
+    if (deviceValue != null && deviceValue >= 0) {
+      return deviceValue;
+    }
+    return _settings.gpsIntervalSeconds;
+  }
+
   String batteryChemistryForDevice(String deviceId) {
     final stored = _settings.batteryChemistryByDeviceId[deviceId];
     if (stored == 'liion') return 'nmc';
@@ -128,6 +136,28 @@ class AppSettingsService extends ChangeNotifier {
     await updateSettings(_settings.copyWith(notifyOnNewAdvert: value));
   }
 
+  Future<void> setAutoSendZeroHopAdvertOnGpsUpdate(bool value) async {
+    await updateSettings(
+      _settings.copyWith(autoSendZeroHopAdvertOnGpsUpdate: value),
+    );
+  }
+
+  Future<void> setGpsIntervalSeconds(
+    int value, {
+    Future<void> Function(int value)? writeToDevice,
+  }) async {
+    await updateSettings(_settings.copyWith(gpsIntervalSeconds: value));
+    if (writeToDevice == null) return;
+    try {
+      await writeToDevice(value);
+    } catch (e) {
+      appLogger.warn(
+        'Failed to write GPS interval to device: $e',
+        tag: 'AppSettings',
+      );
+    }
+  }
+
   Future<void> setAutoRouteRotationEnabled(bool value) async {
     await updateSettings(_settings.copyWith(autoRouteRotationEnabled: value));
   }