Fix type errors and linting issues

- Fix type annotation errors in transport_registry.py and __init__.py
- Fix line length violations in test files (E501 errors)
- Fix missing return type annotations
- Fix cryptography NameAttribute type errors with type: ignore
- Fix ExceptionGroup import for cross-version compatibility
- Fix test failure in test_wss_listen_without_tls_config by handling ExceptionGroup
- Fix len() calls with None arguments in test_tcp_data_transfer.py
- Fix missing attribute access errors on interface types
- Fix boolean type expectation errors in test_js_ws_ping.py
- Fix nursery context manager type errors

All tests now pass and linting is clean.

debug_websocket_url.py

@@ -1,65 +0,0 @@
-#!/usr/bin/env python3
-"""
-Debug script to test WebSocket URL construction and basic connection.
-"""
-
-import logging
-
-from multiaddr import Multiaddr
-
-from libp2p.transport.websocket.multiaddr_utils import parse_websocket_multiaddr
-
-# Configure logging
-logging.basicConfig(level=logging.DEBUG)
-logger = logging.getLogger(__name__)
-
-
-async def test_websocket_url():
-    """Test WebSocket URL construction."""
-    # Test multiaddr from your JS node
-    maddr_str = "/ip4/127.0.0.1/tcp/35391/ws/p2p/12D3KooWQh7p5xP2ppr3CrhUFsawmsKNe9jgDbacQdWCYpuGfMVN"
-    maddr = Multiaddr(maddr_str)
-
-    logger.info(f"Testing multiaddr: {maddr}")
-
-    # Parse WebSocket multiaddr
-    parsed = parse_websocket_multiaddr(maddr)
-    logger.info(
-        f"Parsed: is_wss={parsed.is_wss}, sni={parsed.sni}, rest_multiaddr={parsed.rest_multiaddr}"
-    )
-
-    # Construct WebSocket URL
-    if parsed.is_wss:
-        protocol = "wss"
-    else:
-        protocol = "ws"
-
-    # Extract host and port from rest_multiaddr
-    host = parsed.rest_multiaddr.value_for_protocol("ip4")
-    port = parsed.rest_multiaddr.value_for_protocol("tcp")
-
-    websocket_url = f"{protocol}://{host}:{port}/"
-    logger.info(f"WebSocket URL: {websocket_url}")
-
-    # Test basic WebSocket connection
-    try:
-        from trio_websocket import open_websocket_url
-
-        logger.info("Testing basic WebSocket connection...")
-        async with open_websocket_url(websocket_url) as ws:
-            logger.info("✅ WebSocket connection successful!")
-            # Send a simple message
-            await ws.send_message(b"test")
-            logger.info("✅ Message sent successfully!")
-
-    except Exception as e:
-        logger.error(f"❌ WebSocket connection failed: {e}")
-        import traceback
-
-        logger.error(f"Traceback: {traceback.format_exc()}")
-
-
-if __name__ == "__main__":
-    import trio
-
-    trio.run(test_websocket_url)