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

scripts/check_font_coverage.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+"""Check which characters needed by translations are missing from bundled fonts."""
+import json
+import os
+from fontTools.ttLib import TTFont
+
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+FONTS_DIR = os.path.join(ROOT, 'res', 'fonts')
+LANG_DIR = os.path.join(ROOT, 'res', 'lang')
+
+# Load font cmaps
+cjk = TTFont(os.path.join(FONTS_DIR, 'NotoSansCJK-Subset.ttf'))
+cjk_cmap = set(cjk.getBestCmap().keys())
+
+ubuntu = TTFont(os.path.join(FONTS_DIR, 'Ubuntu-R.ttf'))
+ubuntu_cmap = set(ubuntu.getBestCmap().keys())
+
+combined = cjk_cmap | ubuntu_cmap
+
+print(f"CJK subset font glyphs: {len(cjk_cmap)}")
+print(f"Ubuntu font glyphs: {len(ubuntu_cmap)}")
+print(f"Combined: {len(combined)}")
+print()
+
+for lang in ['zh', 'ja', 'ko', 'ru', 'de', 'es', 'fr', 'pt']:
+    path = os.path.join(LANG_DIR, f'{lang}.json')
+    if not os.path.exists(path):
+        continue
+    with open(path, 'r', encoding='utf-8') as f:
+        data = json.load(f)
+    
+    needed = set()
+    for v in data.values():
+        if isinstance(v, str):
+            for c in v:
+                needed.add(ord(c))
+    
+    missing = sorted(needed - combined)
+    if missing:
+        print(f"{lang}.json: {len(needed)} chars needed, {len(missing)} MISSING")
+        for cp in missing[:20]:
+            c = chr(cp)
+            print(f"  U+{cp:04X} {c}")
+        if len(missing) > 20:
+            print(f"  ... and {len(missing) - 20} more")
+    else:
+        print(f"{lang}.json: OK ({len(needed)} chars, all covered)")