Refactor character name handling in enrichNotificationsWithCharacterNames: Update comments for clarity on character_name and characterName usage. Enhance localization by adding success messages in German and English translations.

frontend/src/i18n/locales/de/message.json

@@ -2,6 +2,7 @@
   "message": {
     "title": "Mitteilung",
     "close": "Schließen",
-    "test": "Test funktioniert"
+    "test": "Test funktioniert",
+    "success": "Die Aktion war erfolgreich."
   }
 }

frontend/src/i18n/locales/en/message.json

@@ -1,6 +1,7 @@
 {
   "message": {
     "title": "Notice",
-    "close": "Close"
+    "close": "Close",
+    "success": "The action was successful."
   }
 }