feat: add language selection feature to settings and update translations

frontend/src/i18n/en.json

@@ -172,7 +172,10 @@
     "changing": "Changing…",
     "passwordChanged": "Password changed successfully",
     "passwordMinLength": "New password must be at least 8 characters",
-    "passwordsDoNotMatch": "Passwords do not match"
+    "passwordsDoNotMatch": "Passwords do not match",
+    "language": "Language",
+    "languageLabel": "Language",
+    "languageDesc": "Select your preferred display language"
   },
   "admin": {
     "administration": "Administration",