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_de.dart

@@ -145,6 +145,18 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get croatian => 'Kroatisch';
 
+  @override
+  String get german => 'Deutsch';
+
+  @override
+  String get spanish => 'Spanisch';
+
+  @override
+  String get french => 'Französisch';
+
+  @override
+  String get italian => 'Italienisch';
+
   @override
   String get locationBroadcasting => 'Standortübertragung';
 
@@ -388,6 +400,16 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get storedPermanently => 'Dauerhaft im Raum gespeichert';
 
+  @override
+  String drawingsSentToPublicChannel(int count, String plural) {
+    return '$count Kartenzeichnung$plural an öffentlichen Kanal gesendet';
+  }
+
+  @override
+  String drawingsSharedToPublicChannel(int success, int total) {
+    return '$success/$total Zeichnungen mit öffentlichem Kanal geteilt';
+  }
+
   @override
   String get notConnectedToDevice => 'Nicht mit Gerät verbunden';
 
@@ -1009,6 +1031,9 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get failed => 'Fehlgeschlagen';
 
+  @override
+  String get broadcast => 'Broadcast';
+
   @override
   String get sarMarkerFoundPerson => 'Person gefunden';