feat: add german, japanese, and chinese translations

adds complete translations for:
- german (de)
- japanese (ja)
- chinese simplified (zh)

builds on the internationalization foundation added in #437.
updates CONTRIBUTING_TRANSLATIONS.md to reflect supported languages.

Author: VirenMohindra

CONTRIBUTING_TRANSLATIONS.md

@@ -154,17 +154,17 @@ Some languages have complex plural rules. For now, use a general form that works
 | Language   | Code | Status            |
 | ---------- | ---- | ----------------- |
 | English    | `en` | Complete (source) |
-| Spanish    | `es` | Complete          |
+| Chinese    | `zh` | Complete          |
 | French     | `fr` | Complete          |
+| German     | `de` | Complete          |
+| Japanese   | `ja` | Complete          |
+| Spanish    | `es` | Complete          |
 | Vietnamese | `vi` | Complete          |
 
 ## Requested Languages
 
 We'd love help with:
 
-- German (`de`)
-- Japanese (`ja`)
-- Chinese (`zh`)
 - Korean (`ko`)
 - Portuguese (`pt`)
 - And more!

src/i18n/languages.ts

@@ -10,7 +10,10 @@ export const LANGUAGE_METADATA: Record<
   { name: string; nativeName: string }
 > = {
   en: { name: "English", nativeName: "English" },
+  de: { name: "German", nativeName: "Deutsch" },
   es: { name: "Spanish", nativeName: "Español" },
   fr: { name: "French", nativeName: "Français" },
+  ja: { name: "Japanese", nativeName: "日本語" },
   vi: { name: "Vietnamese", nativeName: "Tiếng Việt" },
+  zh: { name: "Chinese", nativeName: "中文" },
 };