Add localization support for German, Spanish, French, and Italian

- Updated localization files for French, Croatian, Italian, Slovenian to include translations for German, Spanish, French, and Italian.
- Added new methods for handling drawing messages sent to the public channel in multiple languages.
- Enhanced the Contact model to identify public channels using a dedicated method.
- Implemented echo detection for public channel messages, including tracking and reporting of echoes.
- Updated BLE response handling to support echo detection and tracking of sent messages.
- Modified UI components to reflect new localization strings and echo statuses.

lib/providers/app_provider.dart

@@ -208,6 +208,12 @@ class AppProvider with ChangeNotifier {
       messagesProvider.markMessageDelivered(ackCode, roundTripTimeMs);
     };
 
+    // When an echo is detected for a public channel message (PUSH_CODE_LOG_RX_DATA matched)
+    connectionProvider.onMessageEchoDetected = (messageId, echoCount, snrRaw, rssiDbm) {
+      debugPrint('🔊 [AppProvider] Echo detected - Message: $messageId, Count: $echoCount');
+      messagesProvider.handleMessageEcho(messageId, echoCount, snrRaw, rssiDbm);
+    };
+
     // Wire up MessagesProvider's sendMessageCallback for retry logic
     messagesProvider.sendMessageCallback = ({
       required contactPublicKey,
@@ -284,7 +290,7 @@ class AppProvider with ChangeNotifier {
     try {
       // Get all room contacts (excluding Public Channel)
       final rooms = contactsProvider.rooms
-          .where((room) => room.advName != 'Public Channel')
+          .where((room) => !room.isPublicChannel)
           .toList();
 
       if (rooms.isEmpty) {