fix(i18n): restore pre-existing AppearanceSettings translations

Task 7 inadvertently overwrote 18 carefully-tuned translations across 7 languages
(ar/de/es/fr/ja/ko/pt) with the plan author's slightly different wording while
adding the new themeColor / zoomLevel / resetToDefaults keys. The new additions
remain intact; only the pre-existing keys are reverted to the project's original
translations (e.g. de "Designmodus" instead of "Design-Modus", ja
"システム追従" instead of "システムに従う"). Affects: sectionDescription,
themeMode, placeholder, system, currentTheme.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/i18n/messages/ar.json

@@ -100,13 +100,13 @@
   },
   "AppearanceSettings": {
     "sectionTitle": "مظهر السمة",
-    "sectionDescription": "اختر فاتح أو داكن أو اتباع النظام. يتم حفظ الإعدادات تلقائياً.",
+    "sectionDescription": "اختر الفاتح أو الداكن أو اتباع النظام. يتم حفظ الإعدادات تلقائيًا.",
     "themeMode": "وضع السمة",
     "placeholder": "اختر وضع السمة",
     "system": "اتباع النظام",
     "light": "فاتح",
     "dark": "داكن",
-    "currentTheme": "السمة الحالية: {theme}",
+    "currentTheme": "السمة الفعالة الحالية: {theme}",
     "resolvedTheme": {
       "light": "فاتح",
       "dark": "داكن",