Added Line Of Sight Feature for repeater placement, Added app wide Units Setting (#198)

* feat: add LOS workflow, global units, l10n cleanup, and mobile UI overflow fixes

Squashes prior PR commits into one changeset including: LOS map/service/tests, global metric/imperial unit system adoption, notification/BLE safety fixes, app-wide localization backfill/mojibake cleanup, and responsive UI title/overflow hardening.

* l10n: revert unrelated locale churn for LOS feature

* feat: keep LOS with app-wide unit settings

* fix: resolve post-merge app bar/import analyzer errors

* style: format screen files for CI

lib/services/app_settings_service.dart

@@ -132,4 +132,14 @@ class AppSettingsService extends ChangeNotifier {
       _settings.copyWith(batteryChemistryByDeviceId: updated),
     );
   }
+
+  Future<void> setUnitSystem(UnitSystem value) async {
+    await updateSettings(_settings.copyWith(unitSystem: value));
+  }
+
+  Future<void> setLosUnitSystem(String value) async {
+    await setUnitSystem(
+      value == 'imperial' ? UnitSystem.imperial : UnitSystem.metric,
+    );
+  }
 }