Add OpenLCB over TCP/IP support via GridConnect format

[Copilot]

Implements TCP/IP transport for OpenLCB using the GridConnect ASCII protocol (:X<ID>N<DATA>;), enabling communication with OpenLCB hubs and network tools.

Changes

GridConnect codec (utilities.py)

• to_gridconnect() / from_gridconnect() - encode/decode CAN frames to/from ASCII format

TCP transport (interface.py)

• Accept socket.socket in addition to can.BusABC
• Background thread for TCP message reception
• Auto-detect transport type (CAN vs TCP)

Message conversion (message.py)

• Message.to_gridconnect() / Message.from_gridconnect() methods
• Extracted _parse_frame_info() to eliminate duplication between CAN and TCP parsing

Node compatibility (node.py)

• process_message() handles both can.Message and Message objects

Usage

import socket
import pyolcb

# TCP connection (new)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(('localhost', 12021))
interface = pyolcb.Interface(sock)

# CAN connection (unchanged)
# interface = pyolcb.Interface(can.Bus(...))

# Same API for both transports
node = pyolcb.Node(pyolcb.Address('05.01.01.01.8C.00'), interface)
node.produce(pyolcb.Event(125))

Backward compatible - existing CAN functionality unchanged.

Original prompt

Add support for OpenLCB over TCP/IP

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