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_fr.arb

@@ -232,6 +232,26 @@
     "description": "Option de langue croate"
   },
 
+  "german": "Allemand",
+  "@german": {
+    "description": "Option de langue allemande"
+  },
+
+  "spanish": "Espagnol",
+  "@spanish": {
+    "description": "Option de langue espagnole"
+  },
+
+  "french": "Français",
+  "@french": {
+    "description": "Option de langue française"
+  },
+
+  "italian": "Italien",
+  "@italian": {
+    "description": "Option de langue italienne"
+  },
+
   "locationBroadcasting": "Diffusion de position",
   "@locationBroadcasting": {
     "description": "En-tête de section des paramètres de localisation"
@@ -639,6 +659,24 @@
     "description": "Description de la permanence du stockage dans le salon"
   },
 
+  "drawingsSentToPublicChannel": "{count} dessin{plural} de carte envoyé au Canal Public",
+  "@drawingsSentToPublicChannel": {
+    "description": "Message système lors de l'envoi de dessins au canal public",
+    "placeholders": {
+      "count": {"type": "int"},
+      "plural": {"type": "String"}
+    }
+  },
+
+  "drawingsSharedToPublicChannel": "{success}/{total} dessins partagés sur le Canal Public",
+  "@drawingsSharedToPublicChannel": {
+    "description": "Message de snackbar montrant le nombre de succès pour les dessins partagés sur le canal public",
+    "placeholders": {
+      "success": {"type": "int"},
+      "total": {"type": "int"}
+    }
+  },
+
   "notConnectedToDevice": "Non connecté à l'appareil",
   "@notConnectedToDevice": {
     "description": "Message d'erreur lorsque l'appareil n'est pas connecté pour la messagerie directe"
@@ -1715,6 +1753,11 @@
     "description": "État de livraison : échec"
   },
 
+  "broadcast": "Diffusion",
+  "@broadcast": {
+    "description": "État de livraison pour les messages de canal (pas encore d'échos)"
+  },
+
   "sarMarkerFoundPerson": "Personne trouvée",
   "@sarMarkerFoundPerson": {
     "description": "Type de marqueur SAR : personne trouvée"