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/ko.json

@@ -146,6 +146,11 @@
     "chat_bubble_minimal": "미니멀",
     "chat_bubble_rounded": "둥근",
     "chat_bubble_square": "각진",
+    "chat_buffer_loading": "채팅 버퍼: …",
+    "chat_buffer_preparing": "채팅 버퍼: %d/%d 준비 중…",
+    "chat_buffer_ready": "채팅 버퍼: %d/%d 준비됨",
+    "chat_buffer_sending": "채팅: 메시지 %d개 보내는 중…",
+    "chat_buffer_sending_one": "채팅: 메시지 %d개 보내는 중…",
     "chat_cancel": "취소",
     "chat_contact_added": "연락처 추가됨 — 연락처에서 이름을 변경하세요",
     "chat_contact_request": "연락 요청",