fix: backend unavailable test — use free port + ws.close(timeout=2s)

- Use _free_port() instead of hardcoded 19999 (avoids CI port conflicts)
- Add timeout=2.0 to ws.close() so close handshake never blocks >2s

tests/test_ws_proxy.py

@@ -192,7 +192,9 @@ async def test_fake_client_receives_completion_capabilities(proxy_base_url):
 @pytest.mark.asyncio
 async def test_ws_backend_unavailable_closes_cleanly(proxy_base_url, monkeypatch):
     """If pylsp is unreachable, WebSocket should close gracefully (not crash)."""
-    monkeypatch.setattr("ilsp.server.PYTHON_LSP_PORT", 19999)
+    # Use _free_port() to guarantee nothing is listening (avoids CI port 19999 collisions)
+    dead_port = _free_port()
+    monkeypatch.setattr("ilsp.server.PYTHON_LSP_PORT", dead_port)
 
     ws_url = proxy_base_url.replace("http://", "ws://") + "/python"
     async with aiohttp.ClientSession() as session: