Fix i18n: strip UTF-8 BOM so translations load again.

PowerShell rewrites had added a BOM that made Python json.load fail, so the UI showed raw keys like nav_servers.

translations/en.json

@@ -1,4 +1,4 @@
-{
+{
     "nav_servers":  "Servers",
     "nav_users":  "Users",
     "nav_invites":  "Invite links",

translations/fa.json

@@ -1,4 +1,4 @@
-{
+{
     "nav_servers":  "سرورها",
     "nav_users":  "کاربران",
     "nav_invites":  "لینک دعوت",

translations/fr.json

@@ -1,4 +1,4 @@
-{
+{
     "nav_servers":  "Serveurs",
     "nav_users":  "Utilisateurs",
     "nav_invites":  "Liens d\u0027invitation",

translations/ru.json

@@ -1,4 +1,4 @@
-{
+{
     "nav_servers":  "Серверы",
     "nav_users":  "Пользователи",
     "nav_invites":  "Ссылки",

translations/zh.json

@@ -1,4 +1,4 @@
-{
+{
     "nav_servers":  "服务器",
     "nav_users":  "用户列表",
     "nav_invites":  "邀请链接",