i18n(chat): translate chat note-buffer status strings (8 languages)

The status-bar chat-buffer indicator was hardcoded English. Add semantic keys
(chat_buffer_sending[_one]/preparing/loading/ready) to the English source and
route chatBufferStatusText() through TR()+snprintf like the other counted
strings — a singular/plural pair for the send count, %d/%d for the buffer
fill. Translate all five into de/es/fr/ja/ko/pt/ru/zh (additive JSON edits,
format specifiers preserved so the runtime overlay accepts them), and rebuild
the CJK subset font for the two new glyphs (버퍼's 퍼 U+D37C, 缓冲's 冲 U+51B2).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

res/lang/ja.json

@@ -146,6 +146,11 @@
     "chat_bubble_minimal": "ミニマル",
     "chat_bubble_rounded": "角丸",
     "chat_bubble_square": "角ばった",
+    "chat_buffer_loading": "チャットバッファ：…",
+    "chat_buffer_preparing": "チャットバッファ：%d/%d を準備中…",
+    "chat_buffer_ready": "チャットバッファ：%d/%d 準備完了",
+    "chat_buffer_sending": "チャット：%d 件のメッセージを送信中…",
+    "chat_buffer_sending_one": "チャット：%d 件のメッセージを送信中…",
     "chat_cancel": "キャンセル",
     "chat_contact_added": "連絡先を追加しました — 連絡先で名前を変更できます",
     "chat_contact_request": "連絡リクエスト",