feat: Translate frontend/src/i18n/en.json in ru

94% of minimum 50% translated source file: 'frontend/src/i18n/en.json'
on 'ru'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

frontend/src/i18n/ru.json

@@ -42,7 +42,7 @@
     "update": "Обновить",
     "upload": "Загрузить",
     "openFile": "Открыть файл",
-    "discardChanges": "Discard"
+    "discardChanges": "Отказаться"
   },
   "download": {
     "downloadFile": "Скачать файл",