feat(config): make EnvironmentConfig runtime-overridable

Convert EnvironmentConfig's compile-time *.fromEnvironment constants into
getters that resolve `runtime override ?? compile-time default`, and add
applyOverrides/clearOverrides/hasOverride. This lets an embedder (e.g. the theme
configurator's realtime preview) inject the whole dart-define set at runtime.
Standalone builds are byte-identical - no overrides are ever applied. The
*__NAME key constants stay const.

Nullable `bool.hasEnvironment(X) ? String.fromEnvironment(X) : null` fallbacks
move to `static const _*_ENV` fields, since hasEnvironment can only be used in a
const context.

Members become getters, so const-context usages are adjusted (const -> final /
drop const): main_shell.dart polling Durations, feature_access.dart
CallTriggerConfig, logzio_logging_service.dart, autoprovision, push_tokens,
several screen-page titles, and the screenshots subpackage (router + test +
main_screen_screenshot).

Author: SERDUN

lib/app/router/main_shell.dart

@@ -739,36 +739,36 @@ class _MainShellState extends State<MainShell> with WidgetsBindingObserver {
     return [
       PollingRegistration(
         listener: context.read<UserRepository>(),
-        interval: const Duration(seconds: EnvironmentConfig.USER_REPOSITORY_POLLING_INTERVAL_SECONDS),
+        interval: Duration(seconds: EnvironmentConfig.USER_REPOSITORY_POLLING_INTERVAL_SECONDS),
       ),
       PollingRegistration(
         listener: context.read<SystemInfoRepository>(),
-        interval: const Duration(seconds: EnvironmentConfig.SYSTEM_INFO_REPOSITORY_POLLING_INTERVAL_SECONDS),
+        interval: Duration(seconds: EnvironmentConfig.SYSTEM_INFO_REPOSITORY_POLLING_INTERVAL_SECONDS),
       ),
       if (supportsExtensions)
         PollingRegistration(
           listener: context.read<ExternalContactsRepository>(),
-          interval: const Duration(seconds: EnvironmentConfig.EXTERNAL_CONTACTS_REPOSITORY_POLLING_INTERVAL_SECONDS),
+          interval: Duration(seconds: EnvironmentConfig.EXTERNAL_CONTACTS_REPOSITORY_POLLING_INTERVAL_SECONDS),
         ),
       if (isVoicemailsEnabled)
         PollingRegistration(
           listener: context.read<VoicemailRepository>(),
-          interval: const Duration(seconds: EnvironmentConfig.VOICEMAIL_REPOSITORY_POLLING_INTERVAL_SECONDS),
+          interval: Duration(seconds: EnvironmentConfig.VOICEMAIL_REPOSITORY_POLLING_INTERVAL_SECONDS),
         ),
       if (cliSettingsRepository is CallerIdSettingsRepositoryRemoteImpl)
         PollingRegistration(
           listener: cliSettingsRepository,
-          interval: const Duration(seconds: EnvironmentConfig.CALLER_ID_SETTINGS_REPOSITORY_POLLING_INTERVAL_SECONDS),
+          interval: Duration(seconds: EnvironmentConfig.CALLER_ID_SETTINGS_REPOSITORY_POLLING_INTERVAL_SECONDS),
         ),
       if (favoritesRepository is FavoritesRepositorySyncableImpl)
         PollingRegistration(
           listener: favoritesRepository,
-          interval: const Duration(seconds: EnvironmentConfig.FAVORITES_REPOSITORY_POLLING_INTERVAL_SECONDS),
+          interval: Duration(seconds: EnvironmentConfig.FAVORITES_REPOSITORY_POLLING_INTERVAL_SECONDS),
         ),
       if (sipSubscriptionsRepository is SipSubscriptionsRepositorySyncableImpl)
         PollingRegistration(
           listener: sipSubscriptionsRepository,
-          interval: const Duration(seconds: EnvironmentConfig.SIP_SUBSCRIPTIONS_REPOSITORY_POLLING_INTERVAL_SECONDS),
+          interval: Duration(seconds: EnvironmentConfig.SIP_SUBSCRIPTIONS_REPOSITORY_POLLING_INTERVAL_SECONDS),
         ),
     ];
   }

lib/common/logging/logzio_logging_service.dart

@@ -15,8 +15,8 @@ class LogzioLoggingService implements RemoteLoggingService {
   static LogzioLoggingService? fromEnvironment(bool enabled) {
     if (!enabled) return null;
 
-    const url = EnvironmentConfig.REMOTE_LOGZIO_LOGGING_URL;
-    const token = EnvironmentConfig.REMOTE_LOGZIO_LOGGING_TOKEN;
+    final url = EnvironmentConfig.REMOTE_LOGZIO_LOGGING_URL;
+    final token = EnvironmentConfig.REMOTE_LOGZIO_LOGGING_TOKEN;
     if (url == null || token == null) return null;
 
     final minLevel = Level.LEVELS.firstWhere((l) => l.name == EnvironmentConfig.REMOTE_LOGZIO_LOG_LEVEL);

lib/data/feature_access.dart

@@ -402,7 +402,7 @@ abstract final class CallMapper {
         isBlindTransferEnabled: transferConfig.enableBlindTransfer,
         isAttendedTransferEnabled: transferConfig.enableAttendedTransfer,
       ),
-      triggerConfig: const CallTriggerConfig(
+      triggerConfig: CallTriggerConfig(
         smsFallback: SmsFallbackTriggerConfig(
           enabled: EnvironmentConfig.CALL_TRIGGER_MECHANISM_SMS,
           available: EnvironmentConfig.CALL_TRIGGER_MECHANISM_SMS,

lib/environment_config.dart

@@ -34,11 +34,11 @@ class AutoprovisionScreenPage extends StatelessWidget {
     final tenantId = this.tenantId ?? '';
     final oldTenant = context.read<AppBloc>().state.session.tenantId;
 
-    const defaultCoreUrl = EnvironmentConfig.CORE_URL ?? EnvironmentConfig.DEMO_CORE_URL;
+    final defaultCoreUrl = EnvironmentConfig.CORE_URL ?? EnvironmentConfig.DEMO_CORE_URL;
     final coreUrl = this.coreUrl;
     final oldCoreUrl = context.read<AppBloc>().state.session.coreUrl;
 
-    const coreVersionConstraint = EnvironmentConfig.CORE_VERSION_CONSTRAINT;
+    final coreVersionConstraint = EnvironmentConfig.CORE_VERSION_CONSTRAINT;
     final config = AutoprovisionConfig(
       configToken: configToken,
       oldToken: oldToken,

lib/features/autoprovision/view/autoprovision_screen_page.dart

@@ -23,7 +23,7 @@ class NumberCdrsScreenPage extends StatelessWidget {
     return BlocProvider(
       create: (context) =>
           NumberCdrsLogCubit(number, context.read<CdrsLocalRepository>(), context.read<CdrsRemoteRepository>())..init(),
-      child: NumberCdrsScreen(title: const Text(EnvironmentConfig.APP_NAME), videoVisible: videoVisible),
+      child: NumberCdrsScreen(title: Text(EnvironmentConfig.APP_NAME), videoVisible: videoVisible),
     );
   }
 }

lib/features/cdrs/features/number_cdrs_log/view/number_cdrs_screen_page.dart

@@ -29,7 +29,7 @@ class RecentCdrsScreenPage extends StatelessWidget {
         ),
       ],
       child: RecentCdrsScreen(
-        title: const Text(EnvironmentConfig.APP_NAME),
+        title: Text(EnvironmentConfig.APP_NAME),
         transferEnabled: featureAccess.callConfig.capabilities.isBlindTransferEnabled,
         videoEnabled: featureAccess.callConfig.capabilities.isVideoCallEnabled,
         chatsEnabled: featureAccess.messagingConfig.chatsPresent,

lib/features/cdrs/view/recent_cdrs_screen_page.dart

@@ -26,7 +26,7 @@ class ContactsScreenPage extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final widget = ContactsScreen(
-      title: const Text(EnvironmentConfig.APP_NAME),
+      title: Text(EnvironmentConfig.APP_NAME),
       sourceTypes: sourceTypes,
       sourceTypeWidgetBuilder: _contactSourceTypeWidgetBuilder,
     );

lib/features/contacts/view/contacts_screen_page.dart

@@ -21,7 +21,7 @@ class FavoritesScreenPage extends StatelessWidget {
     final cdrsEnabled = featureAccess.bottomMenuConfig.getTabEnabled<RecentsBottomMenuTab>()?.supportsCallHistory;
 
     final widget = FavoritesScreen(
-      title: const Text(EnvironmentConfig.APP_NAME),
+      title: Text(EnvironmentConfig.APP_NAME),
       transferEnabled: featureAccess.callConfig.capabilities.isBlindTransferEnabled,
       videoEnabled: featureAccess.callConfig.capabilities.isVideoCallEnabled,
       chatsEnabled: featureAccess.messagingConfig.chatsPresent,

lib/features/favorites/view/favorites_screen_page.dart

@@ -18,7 +18,7 @@ class KeypadScreenPage extends StatelessWidget {
     final featureAccess = context.read<FeatureAccess>();
 
     final widget = KeypadScreen(
-      title: const Text(EnvironmentConfig.APP_NAME),
+      title: Text(EnvironmentConfig.APP_NAME),
       videoEnabled: featureAccess.callConfig.capabilities.isVideoCallEnabled,
       transferEnabled: featureAccess.callConfig.capabilities.isBlindTransferEnabled,
     );