Migrate from electron-store to OS-level secure storage (getSecureStorage)

- Replace `electron-store` with OS-level encrypted storage for secure token, userId, and language management in `LocalSystem` and `keyManager`.
- Add `init-user` IPC handler to initialize user data and manage encryption keys.
- Update login process to handle encrypted storage saving with fallback for macOS issues.
- Add offline warning component to `login/page.tsx` to handle first-time sync requirements.
- Remove `electron-store` and associated dependencies from `package.json` and `package-lock.json`.

lib/locales/en.json

@@ -5,7 +5,11 @@
     "orSocial": "or continue with",
     "noAccount": "Don't have an account yet?",
     "createAccount": "Create one here",
-    "backToLogin": "Back to login"
+    "backToLogin": "Back to login",
+    "offlineWarning": {
+      "title": "First sync required",
+      "message": "An Internet connection is required for your first login to sync your data."
+    }
   },
   "loginForm": {
     "error": {

lib/locales/fr.json

@@ -5,7 +5,11 @@
     "orSocial": "ou continuez avec",
     "noAccount": "Pas encore de compte?",
     "createAccount": "Créez-en un ici",
-    "backToLogin": "Retour à la connexion"
+    "backToLogin": "Retour à la connexion",
+    "offlineWarning": {
+      "title": "Première synchronisation requise",
+      "message": "Une connexion Internet est nécessaire pour votre première connexion afin de synchroniser vos données."
+    }
   },
   "loginForm": {
     "error": {