i18n(validation): publish Laravel lang files + translate to RO and RU

- `php artisan lang:publish` created lang/en/{auth,pagination,passwords,validation}.php
- Copied to lang/ro/ and lang/ru/ and translated 30+ most-used validation
  rules (required, email, min, max, unique, exists, etc.), auth messages
  (failed, password, throttle), and pagination labels (previous/next).
- Fixes 'validation.required' literal appearing on form errors in RO/RU
  locales.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lang/ru/pagination.php

@@ -0,0 +1,19 @@
+<?php
+
+return [
+
+    /*
+    |--------------------------------------------------------------------------
+    | Pagination Language Lines
+    |--------------------------------------------------------------------------
+    |
+    | The following language lines are used by the paginator library to build
+    | the simple pagination links. You are free to change them to anything
+    | you want to customize your views to better match your application.
+    |
+    */
+
+    'previous' => '« Назад',
+    'next' => 'Далее »',
+
+];