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

98% 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

@@ -86,7 +86,7 @@
     "csvSeparators": {
       "comma": "Запятая (,)",
       "semicolon": "Точка с запятой (;)",
-      "both": "(,) и (;) одновременно"
+      "both": "Сразу (,) и (;)"
     }
   },
   "help": {