feat: Russian language (#148)

* feat: russian (Русский) language

* chore: correct translate

* chore: correct "System prompt" translate

next-i18next.config.js

@@ -3,7 +3,7 @@ const path = require("path");
 module.exports = {
   i18n: {
     defaultLocale: "en",
-    locales: ["en", "zh"],
+    locales: ["en", "zh", "ru"],
   },
   localePath:
     typeof window === "undefined"