New tools for RS-485 half-duplex communication: - check_rs485_support: Detect hardware RS-485 capability via udev/ioctl Reports driver type (FTDI/CP210x/CH340), kernel support, and recommendations - rs485_transact: Send request and receive response with automatic TX/RX turnaround timing. Handles manual RTS control when needed. - rs485_scan_addresses: Scan bus for responding devices (1-247) Useful for Modbus device discovery