Add basic privilege check

assets/translations/strings_en.i18n.json

@@ -240,6 +240,8 @@
         "singbox": {
             "unexpected": "Unexpected Service Error",
             "serviceNotRunning": "Service is not running",
+            "missingPrivilege": "Missing Privilege",
+            "missingPrivilegeMsg": "VPN mode requires administrator privileges. Either relaunch the app as administrator or change service mode.",
             "invalidConfigOptions": "Invalid configuration options",
             "invalidConfig": "Invalid Configuration",
             "create": "Service creation error",