i18n(chat): translate chat_toast_too_long (8 languages)

The one remaining English-only chat string (the "message too long" toast from
the larger-messages composer cap) is now translated into de/es/fr/pt/ru/zh/ja/ko
(2503 -> 2504 keys each), consistent with each file's terminology and formality.
No new CJK glyphs — all covered by the existing subset font.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

res/lang/ko.json

@@ -387,6 +387,7 @@
     "chat_toast_not_connected": "연결되지 않음 — 채팅 메시지가 전송되지 않았습니다.",
     "chat_toast_request_compose_failed": "연락 요청을 작성할 수 없습니다 (잘못된 주소 / 텍스트?).",
     "chat_toast_request_queued": "연락 요청이 대기열에 추가되었습니다.",
+    "chat_toast_too_long": "메시지가 너무 깁니다. 줄여서 다시 보내세요.",
     "chat_toast_waiting_reply": "상대방이 답장해야 메시지를 보낼 수 있습니다.",
     "chat_today": "오늘",
     "chat_ts_12h": "12시간",