fix(i18n): nest common.changeLanguage under common object

- Restructured the `common.changeLanguage` key to be nested under a `common` object in `en.json`, `fr.json`, and `zh.json`.
- This change improves the organization of the translation files and aligns with best practices for i18next.

web/src/i18n/locales/en.json

@@ -2130,5 +2130,7 @@
   "域名黑名单": "Domain Blacklist",
   "白名单": "Whitelist",
   "黑名单": "Blacklist",
-  "common.changeLanguage": "Change Language"
+  "common": {
+    "changeLanguage": "Change Language"
+  }
 }