style(design): apply Minimal Dark Mode design system\n\n- Switched to complete Dark Mode (OLED-friendly)\n- Established standard color palette matching modern technical aesthetics\n- Changed font to Plus Jakarta Sans for increased legibility\n- Enforced dark mode as default in App.tsx\n- Fixed several React cascading render (setState in useEffect) warnings

openspec/changes/localize-app-chinese-default/design.md

@@ -1,30 +1,30 @@
-# Design: Multilingual Support
-
-## Architecture
-
-The application uses `react-i18next` for i18n and `i18next-browser-languagedetector` for language detection. Configuration is centralized in `src/localization/i18n.ts`.
-
-### Language Resources
-
-Translation resources are built as JSON objects in `i18n.ts` (or split into files if they grow large).
-We add a `zh-CN` key in the `resources` object.
-
-### Default Language Strategy
-
-We introduce the `LanguageDetector` plugin.
-`i18n.use(LanguageDetector).init({...})` is configured to check `localStorage` first, then `navigator` (browser/system language).
-`fallbackLng` remains `'en'` as the final fallback.
-
-### Key Mapping
-
-Existing English strings are mapped to semantic keys (for example, `home.title`, `settings.theme`).
-
-## Data Flow
-
-1. App starts.
-2. `i18next` initializes and determines language via `LanguageDetector`:
-   * Check whether `localStorage` has a saved preference.
-   * If not, check `navigator.language`.
-   * If detected language is supported (`en` or `zh-CN`), use it.
-   * Otherwise, use `fallbackLng` (`en`).
-3. Components use `useTranslation` to resolve strings for the active language.
+# Design: Multilingual Support
+
+## Architecture
+
+The application uses `react-i18next` for i18n and `i18next-browser-languagedetector` for language detection. Configuration is centralized in `src/localization/i18n.ts`.
+
+### Language Resources
+
+Translation resources are built as JSON objects in `i18n.ts` (or split into files if they grow large).
+We add a `zh-CN` key in the `resources` object.
+
+### Default Language Strategy
+
+We introduce the `LanguageDetector` plugin.
+`i18n.use(LanguageDetector).init({...})` is configured to check `localStorage` first, then `navigator` (browser/system language).
+`fallbackLng` remains `'en'` as the final fallback.
+
+### Key Mapping
+
+Existing English strings are mapped to semantic keys (for example, `home.title`, `settings.theme`).
+
+## Data Flow
+
+1. App starts.
+2. `i18next` initializes and determines language via `LanguageDetector`:
+   * Check whether `localStorage` has a saved preference.
+   * If not, check `navigator.language`.
+   * If detected language is supported (`en` or `zh-CN`), use it.
+   * Otherwise, use `fallbackLng` (`en`).
+3. Components use `useTranslation` to resolve strings for the active language.