get_board_status()/load_from_board()/write_to_board() kept the serial
link open indefinitely after use (VersaPadLink._ensure_open() never
closes on its own). Any session that called one of these left the COM
port locked for VersaGUI/desktop_viewer/server.py's board fallback
until the MCP server process was killed. Close the link in a finally
block after each call instead.