feat(display): add configurable multi-backend display system

engine/websocket_display.py

@@ -193,11 +193,9 @@ class WebSocketDisplay:
     def _run_async(self, coro):
         """Run coroutine in background."""
         try:
-            loop = asyncio.new_event_loop()
-            asyncio.set_event_loop(loop)
-            loop.run_until_complete(coro)
-        except Exception:
-            pass
+            asyncio.run(coro)
+        except Exception as e:
+            print(f"WebSocket async error: {e}")
 
     def start_server(self):
         """Start the WebSocket server in a background thread."""
@@ -224,6 +222,8 @@ class WebSocketDisplay:
         if self._http_thread is not None:
             return
 
+        self._http_running = True
+
         self._http_running = True
         self._http_thread = threading.Thread(
             target=self._run_async, args=(self._run_http_server(),), daemon=True