Streaming data via StreamProxy currently causes the Grid to reset its scroll position to the top on every chunk load.
This happens because Store.onCollectionMutate fires load events without the postChunkLoad flag, causing GridBody to treat each chunk as a new dataset.

Fix:
Update src/data/Store.mjs to include postChunkLoad: !!me.isStreaming in the load event payload triggered by onCollectionMutate.
This allows the Grid to maintain the user's scroll position while data streams in.