feat: Make ENABLE_WEBSOCKET_SUPPORT disable polling entirely to allow multiple replicas without sticky sessions.

See https://socket.io/docs/v4/using-multiple-nodes/ for details why this was done.

Also create a redis key to track which replica is running the cleanup job

backend/open_webui/main.py

@@ -264,6 +264,7 @@ from open_webui.env import (
     WEBUI_SESSION_COOKIE_SECURE,
     WEBUI_AUTH_TRUSTED_EMAIL_HEADER,
     WEBUI_AUTH_TRUSTED_NAME_HEADER,
+    ENABLE_WEBSOCKET_SUPPORT,
     BYPASS_MODEL_ACCESS_CONTROL,
     RESET_CONFIG_ON_START,
     OFFLINE_MODE,
@@ -932,6 +933,7 @@ async def get_app_config(request: Request):
             "enable_api_key": app.state.config.ENABLE_API_KEY,
             "enable_signup": app.state.config.ENABLE_SIGNUP,
             "enable_login_form": app.state.config.ENABLE_LOGIN_FORM,
+            "disable_websocket_polling": ENABLE_WEBSOCKET_SUPPORT,
             **(
                 {
                     "enable_web_search": app.state.config.ENABLE_RAG_WEB_SEARCH,