docs: restore i18n error codes reference

Author: onmax

docs/content/4.integrations/4.i18n.md

@@ -120,6 +120,21 @@ export default defineServerAuth(() => ({
 }))
 ```
 
+## Error Codes Reference
+
+| Code | Default Message |
+|------|-----------------|
+| `USER_NOT_FOUND` | User not found |
+| `INVALID_PASSWORD` | Invalid password |
+| `INVALID_EMAIL_OR_PASSWORD` | Invalid email or password |
+| `EMAIL_NOT_VERIFIED` | Email not verified |
+| `SESSION_EXPIRED` | Session expired |
+| `INVALID_TOKEN` | Invalid token |
+| `USER_ALREADY_EXISTS` | User already exists |
+| `INVALID_EMAIL` | Invalid email |
+| `PASSWORD_TOO_SHORT` | Password too short |
+| `RATE_LIMIT_EXCEEDED` | Too many requests |
+
 ::callout{icon="i-lucide-book" to="https://www.better-auth.com/docs/concepts/client#error-codes"}
 See [Better Auth Error Codes](https://www.better-auth.com/docs/concepts/client#error-codes) for the complete list of error codes.
 ::