界面渲染 only takes effect at Server startup, so the setting already told the
user to restart the IME process but offered no way to do it outside the
Ctrl+Shift+Alt+R developer shortcut. Add a 重启 button in the same section.
Settings runs in its own process, so the request travels the Aux pipe — the
supported cross-integrity control path the config notifications already use —
and the Server exits with the Watchdog restart code. The shortcut and the
button now share RestartServerProcess().