i18n(chat): translate the chat send/receive toasts into all 8 languages

The HushChat UI labels were already translated, but the send-path
notifications (not-connected, no-z-address, waiting-for-reply, compose
failures, contact-request queued, lite busy) were still hardcoded English.
Route all eight call sites in app_network.cpp through TR() with seven new
keys (the three "no z-address" variants unified into chat_toast_no_zaddr),
add the English fallbacks in i18n.cpp, and translate the keys into de/es/fr/
ja/ko/pt/ru/zh — reusing each file's existing chat_* terminology (z-address,
contact request, message) for consistency. Additive only (950 -> 957 keys
per language). CJK subset font rebuilt to cover the new zh/ja/ko glyphs.

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

res/lang/ko.json

@@ -123,6 +123,13 @@
     "chat_select_hint": "볼 대화를 선택하세요.",
     "chat_send": "전송",
     "chat_send_failed": "전송 안 됨",
+    "chat_toast_compose_failed": "메시지를 작성할 수 없습니다 (너무 긴가요?).",
+    "chat_toast_lite_busy": "이미 전송이 진행 중이거나 열린 지갑이 없습니다.",
+    "chat_toast_no_zaddr": "채팅을 보낼 z-주소가 없습니다.",
+    "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_waiting_reply": "상대방이 답장해야 메시지를 보낼 수 있습니다.",
     "chat_waiting_reply": "상대방의 답장을 기다리는 중입니다 — 답장하면 메시지를 보낼 수 있습니다.",
     "chat_you": "나",
     "choose_icon": "아이콘 선택",