fix: add missing translations and fix namespace usage

- Fix srt-player to use srtT namespace for error messages
- Add deck_id.enterLanguageName and language labels (english, chinese, japanese, korean)
- Add memorize.review.nextCard translation
- Update all 8 locales with consistent translations

messages/ko-KR.json

@@ -165,6 +165,11 @@
     "sentencePlaceholder": "문장 입력",
     "wordPlaceholder": "단어 입력",
     "queryLang": "검색 언어",
+    "enterLanguageName": "언어 이름을 입력하세요",
+    "english": "영어",
+    "chinese": "중국어",
+    "japanese": "일본어",
+    "korean": "한국어",
     "meanings": "의미",
     "addMeaning": "의미 추가",
     "partOfSpeech": "품사",
@@ -297,6 +302,7 @@
       "ease": "난이도",
       "lapses": "실패 횟수",
       "showAnswer": "정답 보기",
+      "nextCard": "다음",
       "again": "다시",
       "hard": "어려움",
       "good": "좋음",