fix: add 3s timeout to LSP backend connection (handles CI firewall drops)

asyncio.open_connection hangs indefinitely when backend port is silently
dropped. Add wait_for(timeout=3.0) so the WS close frame is always sent
within the test's 5s window.

ilsp/server.py

@@ -67,8 +67,10 @@ async def _ws_proxy(request: web.Request, host: str, port: int) -> web.WebSocket
     await ws.prepare(request)
 
     try:
-        tcp_reader, tcp_writer = await asyncio.open_connection(host, port)
-    except OSError as exc:
+        tcp_reader, tcp_writer = await asyncio.wait_for(
+            asyncio.open_connection(host, port), timeout=3.0
+        )
+    except (OSError, asyncio.TimeoutError) as exc:
         logger.error("Cannot connect to LSP on %s:%d — %s", host, port, exc)
         await ws.close(code=1011, message=b"LSP backend unavailable")
         return ws