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/l10n/app_localizations_fr.dart

@@ -145,6 +145,18 @@ class AppLocalizationsFr extends AppLocalizations {
   @override
   String get croatian => 'Croate';
 
+  @override
+  String get german => 'Allemand';
+
+  @override
+  String get spanish => 'Espagnol';
+
+  @override
+  String get french => 'Français';
+
+  @override
+  String get italian => 'Italien';
+
   @override
   String get locationBroadcasting => 'Diffusion de position';
 
@@ -389,6 +401,16 @@ class AppLocalizationsFr extends AppLocalizations {
   @override
   String get storedPermanently => 'Stocké de manière permanente dans le salon';
 
+  @override
+  String drawingsSentToPublicChannel(int count, String plural) {
+    return '$count dessin$plural de carte envoyé au Canal Public';
+  }
+
+  @override
+  String drawingsSharedToPublicChannel(int success, int total) {
+    return '$success/$total dessins partagés sur le Canal Public';
+  }
+
   @override
   String get notConnectedToDevice => 'Non connecté à l\'appareil';
 
@@ -1010,6 +1032,9 @@ class AppLocalizationsFr extends AppLocalizations {
   @override
   String get failed => 'Échec';
 
+  @override
+  String get broadcast => 'Diffusion';
+
   @override
   String get sarMarkerFoundPerson => 'Personne trouvée';