feat: Translate frontend/src/i18n/en.json in fr

99% of minimum 50% translated source file: 'frontend/src/i18n/en.json'
on 'fr'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

frontend/src/i18n/fr.json

@@ -42,7 +42,8 @@
     "update": "Mettre à jour",
     "upload": "Importer",
     "openFile": "Ouvrir le fichier",
-    "discardChanges": "Annuler"
+  "discardChanges": "Annuler",
+  "saveChanges": "Save changes"
   },
   "download": {
     "downloadFile": "Télécharger le fichier",
@@ -100,7 +101,10 @@
     "submit": "Se connecter",
     "username": "Utilisateur·ice",
     "usernameTaken": "Le nom d'utilisateur·ice est déjà pris",
-    "wrongCredentials": "Identifiants incorrects !"
+    "wrongCredentials": "Identifiants incorrects !",
+    "logout_reasons": {
+      "inactivity": "You have been logged out due to inactivity."
+    }
   },
   "permanent": "Permanent",
   "prompts": {