feat: CJK font rendering, force quit confirmation, settings i18n

- Rebuild CJK font subset (1421 glyphs) and convert CFF→TTF for
  stb_truetype compatibility, fixing Chinese/Japanese/Korean rendering
- Add force quit confirmation dialog with cancel/confirm actions
- Show force quit tooltip immediately on hover (no delay)
- Translate hardcoded English strings in settings dropdowns
  (auto-lock timeouts, slider "Off" labels)
- Fix mojibake en-dashes in 7 translation JSON files
- Add helper scripts: build_cjk_subset, convert_cjk_to_ttf,
  check_font_coverage, fix_mojibake

res/lang/de.json

@@ -652,7 +652,7 @@
     "show": "Anzeigen",
     "show_hidden": "Ausgeblendete anzeigen (%d)",
     "show_qr_code": "QR-Code anzeigen",
-    "showing_transactions": "Zeige %d–%d von %d Transaktionen (gesamt: %zu)",
+    "showing_transactions": "Zeige %d–%d von %d Transaktionen (gesamt: %zu)",
     "simple_background": "Einfacher Hintergrund",
     "start_mining": "Mining starten",
     "status": "Status",

res/lang/fr.json

@@ -652,7 +652,7 @@
     "show": "Afficher",
     "show_hidden": "Afficher masqués (%d)",
     "show_qr_code": "Afficher le code QR",
-    "showing_transactions": "Affichage %d–%d sur %d transactions (total : %zu)",
+    "showing_transactions": "Affichage %d–%d sur %d transactions (total : %zu)",
     "simple_background": "Arrière-plan simple",
     "start_mining": "Démarrer le minage",
     "status": "Statut",

res/lang/ja.json

@@ -652,7 +652,7 @@
     "show": "表示",
     "show_hidden": "非表示を表示 (%d)",
     "show_qr_code": "QRコードを表示",
-    "showing_transactions": "%d–%d / %d 件の取引を表示中（合計：%zu）",
+    "showing_transactions": "%d–%d / %d 件の取引を表示中（合計：%zu）",
     "simple_background": "シンプル背景",
     "start_mining": "マイニング開始",
     "status": "ステータス",

res/lang/ko.json

@@ -652,7 +652,7 @@
     "show": "표시",
     "show_hidden": "숨겨진 항목 표시 (%d)",
     "show_qr_code": "QR 코드 표시",
-    "showing_transactions": "%d–%d / %d건의 거래 표시 중 (총: %zu)",
+    "showing_transactions": "%d–%d / %d건의 거래 표시 중 (총: %zu)",
     "simple_background": "단순 배경",
     "start_mining": "채굴 시작",
     "status": "상태",

res/lang/pt.json

@@ -652,7 +652,7 @@
     "show": "Mostrar",
     "show_hidden": "Mostrar ocultos (%d)",
     "show_qr_code": "Mostrar Código QR",
-    "showing_transactions": "Mostrando %d–%d de %d transações (total: %zu)",
+    "showing_transactions": "Mostrando %d–%d de %d transações (total: %zu)",
     "simple_background": "Fundo simples",
     "start_mining": "Iniciar Mineração",
     "status": "Status",

res/lang/ru.json

@@ -652,7 +652,7 @@
     "show": "Показать",
     "show_hidden": "Показать скрытые (%d)",
     "show_qr_code": "Показать QR-код",
-    "showing_transactions": "Показано %d–%d из %d транзакций (всего: %zu)",
+    "showing_transactions": "Показано %d–%d из %d транзакций (всего: %zu)",
     "simple_background": "Простой фон",
     "start_mining": "Начать майнинг",
     "status": "Статус",

res/lang/zh.json

@@ -652,7 +652,7 @@
     "show": "显示",
     "show_hidden": "显示已隐藏 (%d)",
     "show_qr_code": "显示二维码",
-    "showing_transactions": "显示第 %d–%d 笔，共 %d 笔交易（总计：%zu）",
+    "showing_transactions": "显示第 %d–%d 笔，共 %d 笔交易（总计：%zu）",
     "simple_background": "简单背景",
     "start_mining": "开始挖矿",
     "status": "状态",