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

98% of minimum 50% translated source file: 'frontend/src/i18n/en.json'
on 'bg'.

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

frontend/src/i18n/bg.json

@@ -260,10 +260,10 @@
     "siteSettings": "Настройки на сървъра"
   },
   "success": {
-    "linkCopied": "Link copied!"
+    "linkCopied": "Връзката е копирана!"
   },
   "time": {
-    "days": "Days",
+    "days": "Дни",
     "hours": "Hours",
     "minutes": "Minutes",
     "seconds": "Seconds",