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/widgets/contacts/contact_tile.dart

@@ -719,7 +719,7 @@ class ContactTile extends StatelessWidget {
                     ),
                   ],
                   // Room Login button for room contacts (except Public Channel)
-                  if (contact.type == ContactType.room && contact.advName != 'Public Channel') ...[
+                  if (contact.type == ContactType.room && !contact.isPublicChannel) ...[
                     const SizedBox(height: 24),
                     SizedBox(
                       width: double.infinity,
@@ -739,7 +739,7 @@ class ContactTile extends StatelessWidget {
                     ),
                   ],
                   // Delete Contact button (for all contact types except Public Channel)
-                  if (contact.advName != 'Public Channel') ...[
+                  if (!contact.isPublicChannel) ...[
                     const SizedBox(height: 12),
                     SizedBox(
                       width: double.infinity,

lib/widgets/map/drawing_toolbar.dart

@@ -482,15 +482,16 @@ class DrawingToolbar extends StatelessWidget {
 
     // Add informational message to chat
     final messagesProvider = Provider.of<MessagesProvider>(context, listen: false);
+    final l10n = AppLocalizations.of(context)!;
     messagesProvider.logSystemMessage(
-      text: '📤 Sent ${drawings.length} map drawing${drawings.length > 1 ? 's' : ''} to Public Channel',
+      text: '📤 ${l10n.drawingsSentToPublicChannel(drawings.length, drawings.length > 1 ? 's' : '')}',
       level: 'info',
     );
 
     ScaffoldMessenger.of(context).showSnackBar(
       SnackBar(
         content: Text(
-          'Shared $successCount/${drawings.length} drawings to Public Channel',
+          l10n.drawingsSharedToPublicChannel(successCount, drawings.length),
         ),
         backgroundColor: successCount == drawings.length
             ? Colors.green