✈️(frontend) add offline support with yhub

The offline support couldn't work with the existing
implementation anymore, because there is no request
to get or save data anymore, everything is handled
with web sockets.
In order to support offline functionality, we
leveraged y-indexeddb to store and synchronize
local changes, ensuring that the application remains
functional even when offline.

src/backend/core/api/viewsets.py

@@ -2969,6 +2969,7 @@ class ConfigView(drf.views.APIView):
             "AI_FEATURE_BLOCKNOTE_ENABLED",
             "AI_FEATURE_LEGACY_ENABLED",
             "API_USERS_SEARCH_QUERY_MIN_LENGTH",
+            "COLLABORATION_LOCAL_DOC_RETENTION_DAYS",
             "COLLABORATION_VERSION_GRANULARITY_MS",
             "COLLABORATION_WS_URL",
             "COLLABORATION_WS_INACTIVITY_TIMEOUT",