Add "invalid_credentials" message to multiple language files

- Updated Spanish (es.json) to include "invalid_credentials": "Credenciales no válidas"
- Updated French (fr.json) to include "invalid_credentials": "Des références non valides"
- Updated Italian (it.json) to include "invalid_credentials": "Credenziali non valide"
- Updated Korean (ko.json) to include "invalid_credentials": "잘못된 자격 증명"
- Updated Dutch (nl.json) to include "invalid_credentials": "Ongeldige referenties"
- Updated Norwegian (no.json) to include "invalid_credentials": "Ugyldig legitimasjon"
- Updated Russian (ru.json) to include "invalid_credentials": "Неверные полномочия"
- Updated Swedish (sv.json) to include "invalid_credentials": "Ogiltiga referenser"
- Updated Chinese (zh.json) to include "invalid_credentials": "无效的凭据"

frontend/src/locales/ko.json

@@ -562,7 +562,8 @@
     "social_auth_desc_1": "소셜 로그인 옵션 및 비밀번호 설정을 관리합니다",
     "social_auth_setup": "소셜 인증 설정",
     "staff_status": "직원 상태",
-    "staff_user": "직원 사용자"
+    "staff_user": "직원 사용자",
+    "invalid_credentials": "잘못된 자격 증명"
   },
   "share": {
     "go_to_settings": "설정으로 이동",